Given y(x) = f(x)g(x). Find the slope of the tangent line to y(x) at x = 7.​

Answer:

Mean: 55.9

Median: 55

Mode: None

Step-by-step explanation:

First, find the mean by dividing the sum by the number of elements:

(72 + 58 + 62 + 38 + 44 + 66 + 42 + 49 + 76 + 52) / 10

= 55.9

Next, find the median by putting the numbers in order and finding the middle one:

38, 42, 44, 49, 52, 58, 62, 66, 72, 76

There is no middle number, so we will take the average of 52 and 58, which is 55.

Lastly, to find the mode, we have to find the number that occurs the most.

All of the numbers occur one time, so there is no mode.

Answer:

The answer is below

Step-by-step explanation:

The box contains 5 red and 4 white balls.

A) The probability that at least 1 ball was​ red = P(both are red) + P(first is red and second is white) + P(first is white second is red)

Given that the first ball was (Upper A )Replaced before the second draw:

P(both are red) = P(red) × P(red) = 5/9 × 5/9 = 25/81

P(first is red and second is white) = P(red) × P(white) = 5/9 × 4/9 = 20/81

P(first is white and second is red) = P(white) × P(red) = 4/9 × 5/9 = 20/81

The probability that at least 1 ball was​ red = 25/81 + 20/81 + 20/81 = 65/81

B) The probability that at least 1 ball was​ red = P(both are red) + P(first is red and second is white) + P(first is white second is red)

Given that the first ball was not Replaced before the second draw:

P(both are red) = P(red) × P(red) = 5/9 × 4/8 = 20/72 (since it was not replaced after the first draw the number of red ball remaining would be 4 and the total ball remaining would be 8)

P(first is red second is white) = P(red) × P(white) = 5/9 × 4/8 = 20/72

P(first is white and second is red) = P(white) × P(red) = 4/9 × 5/8 = 20/72

The probability that at least 1 ball was​ red = 20/72 + 20/72 + 20/72 = 60/72

Answer:

The  number of rainfalls is [tex]n =96[/tex]

The answer to the second question is  no it will not be valid this because from the question we are told that the experiment require one pH reading per rainfall so getting multiply specimens(used for the  pH reading) from  one rainfall will make the experiment invalid.

Step-by-step explanation:

from the question we are told that

    The  standard deviation is  [tex]\sigma = 0.5[/tex]

     The  margin of error is  [tex]E = 0.1[/tex]

Given that the confidence level is  95%  then we can evaluate the level of significance as

                  [tex]\alpha = 100 - 95[/tex]

                  [tex]\alpha = 5 \%[/tex]

                 [tex]\alpha =0.05[/tex]

Next we will obtain the critical value of [tex]\frac{\alpha }{2}[/tex] from the normal distribution table , the value is  [tex]Z_{\frac{\alpha }{2} } = 1.96[/tex]

Generally the sample size is mathematically represented as

           [tex]n = [\frac{Z_{\frac{\alpha }{2} * \sigma }}{ E} ]^2[/tex]

substituting values

             [tex]n = [\frac{1.96 * 0.5 }{ 0.1} ]^2[/tex]

            [tex]n =96[/tex]

The answer to the second question is  no the validity is null this because from the question we are told that the experiment require  one pH reading per rainfall so getting multiply specimens(used for the  pH reading) from  one rainfall will make the experiment invalid

Answer:

1) a) [tex]x = \frac{3}{2}\cdot a[/tex], b) [tex]x = 5-3\cdot a[/tex], c) [tex]x = -a[/tex], d) [tex]x = \frac{5}{2}\cdot a[/tex]

2) a) [tex]x = -\frac{3}{4}[/tex], b) [tex]x = -5[/tex], c) [tex]x = 3[/tex]

Step-by-step explanation:

1) a) [tex]5\cdot x - a = x + 5\cdot a[/tex]

[tex]5\cdot x - x = 5\cdot a + a[/tex]

[tex]4\cdot x = 6\cdot a[/tex]

[tex]x = \frac{3}{2}\cdot a[/tex]

b) [tex]4\cdot x + 3\cdot a = 3\cdot x + 5[/tex]

[tex]4\cdot x - 3\cdot x = 5 - 3\cdot a[/tex]

[tex]x = 5-3\cdot a[/tex]

c) [tex]2\cdot (3\cdot x - a) - 4\cdot (x-a) = 3\cdot (x+a)[/tex]

[tex]6\cdot x -2\cdot a -4\cdot x +4\cdot a = 3\cdot x +3\cdot a[/tex]

[tex]6\cdot x -4\cdot x -3\cdot x = 3\cdot a -4\cdot a +2\cdot a[/tex]

[tex]-x = a[/tex]

[tex]x = -a[/tex]

d) [tex]\frac{2\cdot x}{5} - \frac{x-2\cdot a}{3} = \frac{a}{2}[/tex]

[tex]\frac{6\cdot x-5\cdot (x-2\cdot a)}{15} = \frac{a}{2}[/tex]

[tex]\frac{6\cdot x - 5\cdot x+10\cdot a}{15} = \frac{a}{2}[/tex]

[tex]2\cdot (x+10\cdot a) = 15 \cdot a[/tex]

[tex]2\cdot x = 5\cdot a[/tex]

[tex]x = \frac{5}{2}\cdot a[/tex]

2) a) [tex]\frac{3}{x} + \frac{5}{x+2} = 0[/tex]

[tex]\frac{3\cdot (x+2)+5\cdot x}{x\cdot (x+2)} = 0[/tex]

[tex]3\cdot (x+2) + 5\cdot x = 0[/tex]

[tex]3\cdot x +6 +5\cdot x = 0[/tex]

[tex]8\cdot x = - 6[/tex]

[tex]x = -\frac{3}{4}[/tex]

b) [tex]\frac{7}{x-2} = \frac{5}{x}[/tex]

[tex]7\cdot x = 5\cdot (x-2)[/tex]

[tex]7\cdot x = 5\cdot x -10[/tex]

[tex]2\cdot x = -10[/tex]

[tex]x = -5[/tex]

c) [tex]\frac{2}{x-3}-\frac{4\cdot x}{x^{2}-9} = \frac{7}{x+3}[/tex]

[tex]\frac{2}{x-3} - \frac{4\cdot x}{(x+3)\cdot (x-3)} = \frac{7}{x+3}[/tex]

[tex]\frac{1}{x-3}\cdot \left(2-\frac{4\cdot x}{x+3} \right) = \frac{7}{x+3}[/tex]

[tex]\frac{x+3}{x-3}\cdot \left[\frac{2\cdot (x+3)-4\cdot x}{x+3} \right] = 7[/tex]

[tex]\frac{2\cdot (x+3)-4\cdot x}{x-3} = 7[/tex]

[tex]2\cdot (x+3) -4\cdot x = 7\cdot (x-3)[/tex]

[tex]2\cdot x + 6 - 4\cdot x = 7\cdot x -21[/tex]

[tex]2\cdot x - 4\cdot x -7\cdot x = -21-6[/tex]

[tex]-9\cdot x = -27[/tex]

[tex]x = 3[/tex]

Answer:

1) For every copy she sells, her pay increases by $110

2) Her total pay is 2300

Step-by-step explanation:

1) X is the number of copies she sells. In the equation 110X+ 2300 = Y, X will determine how many times 110 is multiplied. So, for every increase by one in X, Y will also go up by 110

eg.

110(50) + 2300 = 7800   -- if she sells 50 copies

110(51) + 2300 = 7910  -- if she sells 51 copies,

2) If she doesn't sell any copies, the equation becomes 110 * 0 + 2300. Anything multiplied by 0 equals 0, so the equation equals 0 + 2300 = 2300 = Y

Therefore, if she doesn't sell any copies, she will get a pay of $2300  

Answer:

First option

Step-by-step explanation:

Common ratio is greater than 1

Answer:

See below.

Step-by-step explanation:

1 gal = 4 qt

With a full gallon oil tank, you can fill 4 1-qt bottles.

The problem does not mention the number of quarts that go in a case, so there is not enough information to answer the question.

Also, is the full tank really only 1 gallon, or is there a number missing there too?

Answer:

28

Step-by-step explanation:

We need to find the value of [tex]\Sigma_{x=0}^3\ 2x^2[/tex]

We know that,

[tex]\Sigma n^2=\dfrac{n(n+1)(2n+1)}{6}[/tex]

Here, n = 3

So,

[tex]\Sigma n^2=\dfrac{3(3+1)(2(3)+1)}{6}\\\\\Sigma n^2=14[/tex]

So,

[tex]\Sigma_{x=0}^3\ 2x^2=2\times 14\\\\=28[/tex]

So, the value of [tex]\Sigma_{x=0}^3\ 2x^2[/tex] is 28. Hence, the correct option is (d).

Answer:

$34000

Step-by-step explanation:

We can set up a systems of equations, assuming [tex]h[/tex] is the husbands income and [tex]w[/tex] is the wife's income.

h + w = 84000

h = 2w - 18000

We can substitute h into the equation as 2w - 18000:

(2w - 18000) + w = 84000

Combine like terms:

3w - 18000 = 84000

Add 18000 to both sides

3w = 102000

And divide both sides by 3

w = 34000

Now that we know how much the wife earns, we can also find out how much the husband earns by substituting into the equation.

h + 34000  = 84000

h = 50000

Hope this helped!

Complete Question

The  complete question is shown on the first uploaded image

Answer:

  The correct option is C

Step-by-step explanation:

From the question we are told that

      The  number of purple  kernel is  [tex]n_k = 3593[/tex]

        The number of  yellow kernel is  [tex]n_y = 1102[/tex]

Generally the ration of the purple to the yellow kernels is mathematically evaluated as

              [tex]r = \frac{n_k}{n_y}[/tex]

substituting values

              [tex]r = \frac{3593}{1102}[/tex]

              [tex]r = 3.3[/tex]      

              [tex]r \approx 3[/tex]

Therefore the ratio is  

               [tex]1 \ Yellow : 3 \ Purple[/tex]

Answer:

27/35

Step-by-step explanation:

We use combination to solve for this

C(n, r), =nCr = n!/r!(n - r)!

From the question, we are told that:

Four couples are at a party. Four of the eight people are randomly selected to win a prize.

Four couples = 8 people.

= 8C4 = 8!/4! (8 - 4)!

= 70

No person can win more than one prize. ( No person can win more than one prize of the 4 people selected)

This can happen in 4 ways

[4C1 × 3C2 ] × 4=

[4!/1! ×( 4 - 1)!] × [3!/2! ×(3-2)!] × 4 ways

= 4 × 3 × 4 ways

= 48

The probability that both of the members of at least one couple win prizes

48 + 4C2/ 8C4

4C2 = 4!/2!(4 - 2) !

= 6

8C4 = 8C4 = 8!/4! (8 - 4)!

= 70

48 + 6/ 70

= 54/70

= 27/35

Therefore, the probability that both of the members of at least one couple win prizes is 27/35.

The probability that both of the members of at least one couple win prizes is 27/35 and this can be determined by using the given data.

Given :

The following steps can be used in order to determine the probability that both of the members of at least one couple win prizes:

Step 1 - The concept of probability is used in order to determine the probability that both of the members of at least one couple win prizes.

Step 2 - According to the given data, the total number of people is 8.

Step 3 - So, the probability that both of the members of at least one couple win prizes is:

[tex]\rm P =\dfrac{ \;^4C_1\times \;^3C_2\times 4 + \;^4C_2}{\;^8C_4}[/tex]

Step 4 - Simplify the above expression.

[tex]\rm P =\dfrac{48+ 6}{70}[/tex]

[tex]\rm P = \dfrac{27}{35}[/tex]

So, the probability that both of the members of at least one couple win prizes is 27/35.

For more information, refer to the link given below:

https://brainly.com/question/795909

Answer:

x = 4

Step-by-step explanation:

2( 3x + 3) = 8x - 2

6x + 6 = 8x -2

6x + 8 = 8x

8 = 2x

4 = x

It is given that Y is the midpoint of XZ. If XZ = 8x − 2 and YZ = 3x + 3, So the value of x is x = 4.

Midpoint, as the word suggests, means the point which lies in the middle of something.

Midpoint of a line segment means a point which lies in the mid of the given line segment.

We have been given that Y is the midpoint of XZ. If XZ = 8x − 2 and YZ = 3x + 3, we need to find x.

We know that;

2(YZ) = XZ  

Substitute in the values

2( 3x + 3) = 8x - 2

Use the Distributive Property

6x + 6 = 8x -2

6x + 8 = 8x

8 = 2x

4 = x

Switch the sides to make it easier to read

x = 4

It is given that Y is the midpoint of XZ. If XZ = 8x − 2 and YZ = 3x + 3, So the value of x is x = 4.

To learn more about the midpoint click below;

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Answer:

[tex](f/g)(x) = \frac{x + 5}{3x + 5} [/tex]

Step-by-step explanation:

f(x) = 3x² + 10x - 25

g(x) = 9x² - 25

To find (f/g)(x) divide f(x) by g(x)

That's

[tex](f/g)(x) = \frac{3 {x}^{2} + 10x - 25 }{9 {x}^{2} - 25 } [/tex]

Factorize both the numerator and the denominator

For the numerator

3x² + 10x - 25

3x² + 15x - 5x - 25

3x ( x + 5) - 5( x + 5)

(3x - 5 ) ( x + 5)

For the denominator

9x² - 25

(3x)² - 5²

Using the formula

a² - b² = ( a + b)(a - b)

(3x)² - 5² = (3x + 5)(3x - 5)

So we have

[tex](f/g)(x) = \frac{(3x - 5)(x + 5)}{(3x + 5)(3x - 5)} [/tex]

Simplify

We have the final answer as

[tex](f/g)(x) = \frac{x + 5}{3x + 5} [/tex]

Hope this helps you

4) 2x-2y+3 > 0

although it is spelt "26" on the choices

Complete Question

The complete question is shown on the first uploaded image

Answer:

a

    [tex]P(3) = 0.154[/tex]

b

    [tex]P(4) = 0.026[/tex]

c

   [tex]P( X \ge 3 ) = 0.18[/tex]

d

   option C is correct

Step-by-step explanation:

From the question we are told that

      The probability of success is  p =  0.4

      The sample size is n=  4

 This adults believe follow a binomial distribution is because there are only two outcome one is an adult  believes in  reincarnation and the second an adult does not believe in reincarnation

  The probability of  failure is mathematically evaluated as

              [tex]q = 1 - p[/tex]

substituting values

             [tex]q = 1 - 0.4[/tex]

             [tex]q = 0.6[/tex]

Considering a  

The  probability that exactly 3 of the selected adults believe in reincarnation is mathematically represented as

       [tex]P(3) = \left n} \atop {}} \right. C_ 3 * p^3 * q^{n-3}[/tex]

substituting values

     [tex]P(3) = \left 4} \atop {}} \right. C_ 3 * (0.40)^3 * (0.60)^{4-3}[/tex]

Here [tex]\left 4} \atop {}} \right.C_3[/tex] means  4  combination 3 . i have calculated this using a calculator and the value is  

           [tex]\left 4} \atop {}} \right.C_3 = 4[/tex]

So

         [tex]P(3) = 4* (0.4)^3 * (0.6)[/tex]

          [tex]P(3) = 0.154[/tex]

Considering b

The probability that all of the selected adults believe in reincarnation is mathematically represented as

        [tex]P(n) = \left n} \atop {}} \right. C_ n * p^n * q^{n-n}[/tex]

substituting values

         [tex]P(4) = \left 4} \atop {}} \right. C_ 4 * (0.40)^4 * (0.60)^{4-4}[/tex]

Here [tex]\left 4} \atop {}} \right.C_3[/tex] means  4  combination  . i have calculated this using a calculator and the value is  [tex]\left 4} \atop {}} \right.C_4 = 1[/tex]

so

          [tex]P(4) = 1* (0.4)^4 * 1[/tex]

=>       [tex]P(4) = 0.026[/tex]

Considering c

the probability that at least 3 of the selected adults believe in reincarnation is mathematically represented as

     [tex]P( X \ge 3 ) = P(3 ) + P(n )[/tex]

substituting values

    [tex]P( X \ge 3 ) = 0.154 + 0.026[/tex]

     [tex]P( X \ge 3 ) = 0.18[/tex]

From the calculation the probability that all the 4 randomly selected persons believe in reincarnation is  [tex]p(4) = 0.026 < 0.05[/tex]

But the the probability of 3 out of the 4 randomly selected person believing in reincarnation is [tex]P(3) = 0.154 \ which \ is \ > 0.05[/tex]

Hence 3 is not a  significantly high number of adults who believe in reincarnation because the probability that 3 or more of the selected adults believe in reincarnation is greater than 0.05.

Answer:

220m

Step-by-step explanation:

l=85m

b=25m

perimeter=2(l+b)

2(85+25)

2(110)

=220m

perimeter is 220m

Answer:

Step-by-step explanation:

The distance around the field means the perimeter of the field

Since the field is rectangular

Perimeter of a rectangle = 2l + 2w

where l is the length

w is the width

From the question

l = 85m

w = 25m

Perimeter = 2(85) + 2(25)

Perimeter = 170 + 50

The final answer is

Perimeter = 220m

Hope this helps you

Answer:

Step-by-step explanation:

I answered this already a few minutes ago.

Answer:

yes you can

Step-by-step explanation:

you can write algebraic expressions and use variables for the unknown

Answer: 44

Step-by-step explanation:

Answer:

B. $30

Step-by-step explanation:

First, find the amount of the tip.

Multiply the tip rate and taxi fare.

tip rate * taxi fare

The tip rate is 15% and the taxi fare is $25.50

15% * 25.50

Convert 15% to a decimal. Divide 15 by 100 or move the decimal place two spots to the left.

15/100=0.15

15.0 ---> 1.5 ---> 0.15

0.15 * 25.50

3.825

The tip amount is $3.825

Next, find the total amount she paid.

Add the taxi fare and the tip amount.

taxi fare + tip amount

The taxi fare is $25.50 and the tip amount is $3.825

$25.50 + $3.825

$29.325

Round to the nearest dollar. Typically, this would round down to $29, but that is not an answer choice. So, if we round up, the next best answer is $30.

Therefore, the best answer choice is B. $30

Answer:

The null hypothesis [tex]\mathtt{H_0 : \mu = 26500}[/tex]

The alternative hypothesis [tex]\mathtt{H_1 : \mu \neq 26500}[/tex]

Step-by-step explanation:

The summary of the given statistics is:

Population Mean = 26,500

Sample Mean = 30,150

Standard deviation = 10560

sample size = 24

The objective is to state the null hypothesis and the alternate hypothesis.

An hypothesis is a claim with  insufficient information which tends to be challenged into  further testing and experimentation in order to determine if such claim is significant or not.

The null hypothesis is a default hypothesis where there is no statistical significance between the two variables in the hypothesis.

The alternative hypothesis is the research hypothesis that the  researcher is trying to prove.

The null hypothesis [tex]\mathtt{H_0 : \mu = 26500}[/tex]

The alternative hypothesis [tex]\mathtt{H_1 : \mu \neq 26500}[/tex]

The test statistic can be  computed as follows:

[tex]z = \dfrac{\overline X - \mu}{\dfrac{\sigma}{\sqrt{n}}}[/tex]

[tex]z = \dfrac{30150 - 26500}{\dfrac{10560}{\sqrt{24}}}[/tex]

[tex]z = \dfrac{3650}{\dfrac{10560}{4.8989}}[/tex]

[tex]z = \dfrac{3650 \times 4.8989 }{{10560}}[/tex]

z = 1.6933

Step-by-step explanation:

x=rcosθandy=rsinθ,. 7.7. r2=x2+y2andtanθ=yx. 7.8. These formulas can be used to convert from rectangular to polar or from polar to rectangular coordinates.

Step-by-step explanation:

To find the value of y when z = 14 we must first find the relationship between them

The statement

y varies directly as z is written as

y = kz

where k is the constant of proportionality

when y = 180

z = 10

180 = 10k

Divide both sides by 10

k = 18

The formula for the variation is

y = 18z

When z = 14

y = 18(14)

Hope this helps you

Answer:

15x+6u−3

Step-by-step explanation:

This means -3 times -5x, -3 times -2u, and -3 times 1.

Do this and you have, 15x+6u-3.

Step-by-step explanation:

For a left-hand limit, we start at the left side and move right, and see where the function goes as we get close to the x value.

For a right-hand limit, we start at the right side and move left, and see where the function goes as we get close to the x value.

If the two limits are equal, then the limit exists.  Otherwise, it doesn't.

1.  As we approach x = 2 from the left, f(x) approaches -2.

lim(x→2⁻) f(x) = -2

As we approach x = 2 from the right, f(x) approaches 1.

lim(x→2⁺) f(x) = 1

The limits are not the same, so the limit does not exist.

lim(x→2) f(x) = DNE

2. As we approach x = 2 from the left, f(x) approaches 4.

lim(x→2⁻) f(x) = 4

As we approach x = 2 from the right, f(x) approaches 2.

lim(x→2⁺) f(x) = 2

The limits are not the same, so the limit does not exist.

lim(x→2) f(x) = DNE

3. As we approach x = 2 from the left, f(x) approaches 2.

lim(x→2⁻) f(x) = 2

As we approach x = 2 from the right, f(x) approaches 2.

lim(x→2⁺) f(x) = 2

The limits are equal, so the limit exists.

lim(x→2) f(x) = 2

4. As we approach x = 2 from the left, f(x) approaches 2.

lim(x→2⁻) f(x) = 2

As we approach x = 2 from the right, f(x) approaches infinity.

lim(x→2⁺) f(x) = ∞

The limits are not the same, so the limit does not exist.

lim(x→2) f(x) = DNE

Complete Question

The complete question is shown on the first uploaded image

Answer:

the null hypothesis is  [tex]H_o : \mu = 122[/tex]

the alternative hypothesis is [tex]H_a : \mu \ne 122[/tex]

The test statistics is  [tex]t = - 1.761[/tex]

The p-value is  [tex]p = P(Z < t ) = 0.039119[/tex]

so

    [tex]p \ge 0.01[/tex]

Step-by-step explanation:

From the question we are told that

   The population mean is  [tex]\mu = 122[/tex]

     The sample size is  n=  38

    The sample mean is  [tex]\= x = 116 \ feet[/tex]

     The standard deviation is [tex]\sigma = 21[/tex]

Generally the null hypothesis is  [tex]H_o : \mu = 122[/tex]

                the alternative hypothesis is [tex]H_a : \mu \ne 122[/tex]

Generally the test statistics is mathematically evaluated as

         [tex]t = \frac { \= x - \mu }{\frac{ \sigma }{ \sqrt{n} } }[/tex]

substituting values

         [tex]t = \frac { 116 - 122 }{\frac{ 21 }{ \sqrt{ 38} } }[/tex]

         [tex]t = - 1.761[/tex]

The p-value is mathematically represented as

      [tex]p = P(Z < t )[/tex]

From the z- table  

     [tex]p = P(Z < t ) = 0.039119[/tex]

So  

     [tex]p \ge 0.01[/tex]

Answer:

v(m) = 8 + 48m+ 180m² +216m³

Step-by-step explanation:

Let's first of all represent the edge of the the cube as a function of minutes.

Initially the egde= 2feet

As times elapsed , it increases at the rate of 6 feet per min, that is, for every minute ,there is a 6 feet increase.

Let the the egde be x

X = 2 + 6(m)

Where m represent the minutes elapsed.

So we Al know that the volume of an edge = edge³

but egde = x

V(m) = x³

but x= 2+6(m)

V(m) = (2+6m)³

v(m) = 8 + 48m+ 180m² +216m³

The volume of cube as function of m is,   [tex]V(m)=72m[/tex]

Let us consider that edge of cube is a feet.

Since,   The edge is increasing at the rate of 6 feet per minute.

                      [tex]\frac{da}{dt}=6feet/min.[/tex]

Volume of cube , V = [tex]a^{3}[/tex]

            [tex]\frac{dV}{dt} =3a^{2} \frac{da}{dt}[/tex]

Substituting the value of  da/dt in above equation.

We get,     [tex]\frac{dV}{dt}=3a^{2}*(6) =18a^{2} \\\\dV=18a^{2}dt[/tex]

Integrating on both side.

          [tex]V=18a^{2}t[/tex]

Since, number of minutes elapsed is m.

Substitute , t = m and a = 2 feet in above equation.

We get,     [tex]V=18(2)^{2}*m=72m[/tex]

Thus, the volume of cube as function of m is,   [tex]V(m)=72m[/tex]

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https://brainly.com/question/14002029

Now, it look like there is some information missing in the answer. The whole problem should look like this:

Alicia Keys's new album As I Am is climbing the charts, and the manager of Tip Top Tunes expects to sell a lot of copies. Because she has limited shelf space, she can't put out all her copies of the CD at once. On Monday morning, she stocked the display with 40 copies. By the end of the day, some of the copies had been sold. On Tuesday morning, she counted the number of copies left and then added that many more to the shelf. In other words, she doubled the number that was left in the display. At the end of the day, she discovered that she had sold the exact same number of copies as had been sold on Monday. On Wednesday morning, the manager decided to triple the number of copies that had been left in the case after Tuesday. Amazingly, she sold the same number of copies on Wednesday as she had on each of the first two days! But this time, at the end of the day the display case was empty. How many copies of the As I Am CD did she sell each day?

Answer:

She sold 24 copies of the cd each day.

Step-by-step explanation:

In order to solve this problem we must first set our variable up. In this case, since we need to know what the number of sold cd's per day is, that will just be our variable:

x= Number of copies sold.

So we can start setting our equation up. So we take the first part of the problem:

"On Monday morning, she stocked the display with 40 copies. By the end of the day, some of the copies had been sold."

This can be translated as:

40-x

where this expression represents the number of copies left on the shelf by the end of monday.

"On Tuesday morning, she counted the number of copies left and then added that many more to the shelf."

so we represent it like this:

(40-x)+(40-x)

"In other words, she doubled the number that was left in the display."

so the previous expression can be simplified like this:

2(40-x)

"At the end of the day, she discovered that she had sold the exact same number of copies as had been sold on Monday."

so the expression now turns to:

2(40-x)-x   this is the number of copies left by the end of tuesday.

"On Wednesday morning, the manager decided to triple the number of copies that had been left in the case after Tuesday."

this translates to:

3[2(40-x)-x]

This is the number of copies on the shelf by the begining of Wednesday.

"Amazingly, she sold the same number of copies on Wednesday as she had on each of the first two days! But this time, at the end of the day the display case was empty."

this piece of information lets us finish writting our equation:

3[2(40-x)-x] -x = 0

since there were no copies left on the shelf, then the equation is equal to zero.

So now we proceed and solve the equation for x:

3[2(40-x)-x] -x = 0

We simplify it from the inside to the outside.

3[80-2x-x]-x=0

3[80-3x]-x = 0

we now distribute the 3 so we get:

240-9x-x=0

we combine like terms so we get:

240-10x=0

we move the 240 to the other side of the equation so we get:

-10x=-240

and divide both sides into -10 so we get:

x=24

so she sold 24 copies each day.

Answer:

a.  k = -0.01014 s⁻¹

b.  [tex]\mathbf{\dfrac{dy}{dt} = - \dfrac{In(\dfrac{3}{2})}{40}(y-60)}[/tex]

c.  [tex]\mathbf{y(t) = 60+ \dfrac{60 \sqrt{3}}{\sqrt{2}} \ e^{\dfrac{-In(\dfrac{3}{2})\ t}{40}}}[/tex]

d.  y(t) = 130.485°F

Step-by-step explanation:

A hot metal bar is submerged in a large reservoir of water whose temperature is 60°F. The temperature of the bar 20 s after submersion is 120°F. After 1 min submerged, the temperature has cooled to 100°F.

(Let y be measured in degrees Fahrenheit, and t be measured in seconds.)

We are to determine :

a.  Determine the cooling constant k. k = s−1

By applying the new law of cooling

[tex]\dfrac{dT}{dt} = k \Delta T[/tex]

[tex]\dfrac{dT}{dt} = k(T_1-T_2)[/tex]

[tex]\dfrac{dT}{dt} = k (T - 60)[/tex]

Taking the integral.

[tex]\int \dfrac{dT}{T-60} = \int kdt[/tex]

㏑ (T -60) = kt + C

T - 60 = [tex]e^{kt+C}[/tex]

[tex]T = 60+ C_1 e^{kt} ---- (1)[/tex]

After 20 seconds, the temperature of the bar submersion is 120°F

T(20) = 120

From equation (1) ,replace t = 20s and T = 120

[tex]120 = 60 + C_1 e^{20 \ k}[/tex]

[tex]120 - 60 = C_1 e^{20 \ k}[/tex]

[tex]60 = C_1 e^{20 \ k} --- (2)[/tex]

After 1 min i.e 60 sec , the temperature  = 100

T(60) = 100

From equation (1) ; replace t = 60 s and T = 100

[tex]100 = 60 + c_1 e^{60 \ t}[/tex]

[tex]100 - 60 =c_1 e^{60 \ t}[/tex]

[tex]40 =c_1 e^{60 \ t} --- (3)[/tex]

Dividing equation (2) by (3) , we have:

[tex]\dfrac{60}{40} = \dfrac{C_1e^{20 \ k } }{C_1 e^{60 \ k}}[/tex]

[tex]\dfrac{3}{2} = e^{-40 \ k}[/tex]

[tex]-40 \ k = In (\dfrac{3}{2})[/tex]

- 40 k = 0.4054651

[tex]k = - \dfrac{0.4054651}{ 40}[/tex]

k = -0.01014 s⁻¹

b. What is the differential equation satisfied by the temperature y(t)?

Recall that :

[tex]\dfrac{dT}{dt} = k \Delta T[/tex]

[tex]\dfrac{dT}{dt} = \dfrac{- In (\dfrac{3}{2})}{40}(T-60)[/tex]

Since y is the temperature of the body , then :

[tex]\mathbf{\dfrac{dy}{dt} = - \dfrac{In(\dfrac{3}{2})}{40}(y-60)}[/tex]

(c) What is the formula for y(t)?

From equation (1) ;

where;

[tex]T = 60+ C_1 e^{kt} ---- (1)[/tex]

Let y be measured in degrees Fahrenheit

[tex]y(t) = 60 + C_1 e^{-\dfrac{In (\dfrac{3}{2})}{40}t}[/tex]

From equation (2)

[tex]C_1 = \dfrac{60}{e^{20 \times \dfrac{-In(\dfrac{3}{2})}{40}}}[/tex]

[tex]C_1 = \dfrac{60}{e^{-\dfrac{1}{2} {In(\dfrac{3}{2})}}}[/tex]

[tex]C_1 = \dfrac{60}{e^ {In(\dfrac{3}{2})^{-1/2}}}}[/tex]

[tex]C_1 = \dfrac{60}{\sqrt{\dfrac{2}{3}}}[/tex]

[tex]C_1 = \dfrac{60 \times \sqrt{3}}{\sqrt{2}}}[/tex]

[tex]\mathbf{y(t) = 60+ \dfrac{60 \sqrt{3}}{\sqrt{2}} \ e^{\dfrac{-In(\dfrac{3}{2})\ t}{40}}}[/tex]

(d) Determine the temperature of the bar at the moment it is submerged.

At the moment it is submerged t = 0

[tex]\mathbf{y(0) = 60+ \dfrac{60 \sqrt{3}}{\sqrt{2}} \ e^{\dfrac{-In(\dfrac{3}{2})\ 0}{40}}}[/tex]

[tex]\mathbf{y(t) = 60+ \dfrac{60 \sqrt{3}}{\sqrt{2}} }[/tex]

y(t) = 60 + 70.485

y(t) = 130.485°F

Step-by-step explanation:

C = Amount (A) - Principal (P)

Where

C is the compound interest

To find the amount we use the formula

[tex]A = P ({1 + \frac{r}{100} })^{n} [/tex]

where

P is the principal

r is the rate

n is the period / time

From the question

P = Rs 12, 000

r = 5%

n = 3 years

Substitute the values into the above formula

That's

[tex]A = 12000 ({1 + \frac{5}{100} })^{3} \\ A = 12000(1 + 0.05)^{3} \\ A = 12000 ({1.05})^{3} [/tex]

We have the answer as

Compound interest = 13891.50 - 12000

Hope this helps you

Answer:

The width is  [tex]w = 282.8[/tex]

Step-by-step explanation:

From the question we are told that

  The sample size is n =  50

  The  population standard deviation is  [tex]\sigma = \$ 1000[/tex]

   The sample size is  [tex]\= x = \$ 15,000[/tex]

Given that the confidence level is  90%  then the level of significance can be mathematically represented as

             [tex]\alpha = 100 - 90[/tex]  

             [tex]\alpha = 10 \%[/tex]  

              [tex]\alpha = 0.10[/tex]

Next we obtain the critical value of  [tex]\frac{\alpha }{2}[/tex] from the  normal distribution table, the value is  

             [tex]Z_{\frac{0.10 }{2} } = 1.645[/tex]

Generally the margin of error is mathematically represented as

               [tex]E = Z_{\frac{0.10}{2} } * \frac{\sigma }{\sqrt{n} }[/tex]

substituting values

                 [tex]E = 1.645 * \frac{1000 }{\sqrt{50 }}[/tex]

=>                [tex]E = 141.42[/tex]

  The width of the 90%  confidence level is mathematically represented as

                      [tex]w = 2 * E[/tex]

substituting values

                       [tex]w = 2 * 141.42[/tex]

                       [tex]w = 282.8[/tex]