The amount of time a certain brand of light bulb lasts is normally distributed with a mean of 1400 hours and a standard deviation of 75 hours. What is the probability that a randomly chosen light bulb will last less than 1380 hours, to the nearest thousandth?

Answers

Answer 1

Answer:

0.394 = 39.4% probability that a randomly chosen light bulb will last less than 1380 hours

Step-by-step explanation:

Problems of normally distributed samples are solved using the z-score formula.

In a set with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the zscore of a measure X is given by:

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

In this question, we have that:

[tex]\mu = 1400, \sigma = 75[/tex]

What is the probability that a randomly chosen light bulb will last less than 1380 hours, to the nearest thousandth?

This is the pvalue of Z when X = 1380. So

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

[tex]Z = \frac{1380 - 1400}{75}[/tex]

[tex]Z = -0.27[/tex]

[tex]Z = -0.27[/tex] has a pvalue of 0.394

0.394 = 39.4% probability that a randomly chosen light bulb will last less than 1380 hours


Related Questions

−5y=−5
7x+6y=7

Is (5,1) a solution of the system

Answers

Answer:no, (5,1) is not a solution for the equation. (1/7,1) will be a solution for the equation.

Step-by-step explanation:

one way to do it is to plug 1 as the y-value into the first equation which does work but when you plug 5 as the x-value and 1 as the y-value in the second equation, it will get you to 41 which does not match so it will not be an equation. the other way to check is to solve by substitution which for the first equation, you divide both side by -5 and get y=1 then substitute y with 1 in the second equation and subtract both side by 6 and get 7x=1 and divide both side by 7 to get 1/7. the y-value match but the x-value don't so (5,1) is not a solution.

A wedge of cheese in the shape of a triangular prism is shown below.
​Find the surface area of the cheese.

_______Square feet

Answers

Answer:

[tex]144 $ Square feet[/tex]

Step-by-step explanation:

The given triangular prism comprises of two equal right triangles and three rectangles.

The Surface Area of the Prism

=Area of Two Triangles + Area of Three Rectangles

[tex]=2(0.5X6X8)+(6X4)+(10X4)+(8X4)\\=48+24+40+32\\=144 $ Square feet[/tex]

Answer: 144

Step-by-step explanation:32+24+4-+48=144

A dietician believes that people who eat a high-fiber cereal as part of their breakfast will consume, on average, fewer calories at lunch than people who do not eat a high-fiber cereal as part of their breakfast. To test this claim, he measured the lunchtime calorie intake of 49 adults who did eat a high-fiber cereal for breakfast on a given day (group 1). For those individuals, the average number of calories consumed at lunch was 609.86, with a standard deviation of 55.96 calories. He also measured the lunchtime calorie intake of 78 adults who did not eat a high-fiber cereal for breakfast on a given day (group 2). For those individuals, the average number of calories consumed at lunch was 641.02, with a standard deviation of 109.14 calories. The dietician wishes to test this claim at the 5% significance level.

If Welch's two-sample test for equality of means is used, then what is the value of the test statistic tobs, rounded to two decimal places?

Answers

Answer:

The calculated value Z = 1.8368 < 1.96 at 0.05 level of significance

The null hypothesis is accepted

The samples have been drawn from the same Population

Step-by-step explanation:

Step(i):-

Given first sample size 'n₁' = 49

Mean of the first sample 'x₁⁻ = 609.86

Standard deviation of the sample S₁ = 55.96 calories

Given first sample size 'n₂' = 78

Mean of the first sample 'x₂⁻ = 641.02

Standard deviation of the sample S₂ = 109.14 calories

Step(ii):-

Null hypothesis : H₀: x₁⁻ = x₂⁻

Alternative Hypothesis : H₁: x₁⁻ ≠ x₂⁻

Level of significance ∝ = 0.05

Test statistic

[tex]Z = \frac{x^{-} _{1}-x^{-} _{2} }{\sqrt{S.D^2(\frac{1}{n_{1} } }+\frac{1}{n_{2} } }[/tex]

where

 [tex]S.D^{2} = \frac{n_{1} S^2_{1}+ n_{2} S^2_{2} }{n_{1} + n_{2} -2}[/tex]

 [tex]= \frac{49 X (55.96)^2+ 78X(109.14)^2 }{49 + 78 }[/tex]

 σ² =  8660.357

Step(iii):-

Test statistic

[tex]Z = \frac{x^{-} _{1}-x^{-} _{2} }{\sqrt{S.D^2(\frac{1}{n_{1} } }+\frac{1}{n_{2} } }[/tex]

[tex]= \frac{ 609.86-641.02 }{\sqrt{8660.357(\frac{1}{49 } }+\frac{1}{78 } ) }[/tex]

[tex]Z = \frac{-31.16}{16.9638} = -1.8368[/tex]

|Z| = |-1.8368| = 1.8368

The tabulated value Z₀.₉₅ = 1.96

The calculated value = 1.8368 < 1.96 at 0.05 level of significance

The null hypothesis is accepted

Final answer:-

The samples have been drawn from the same Population

     

What is the length of AC? Brainliest for right answer

Answers

Answer:

2.3 units

Step-by-step explanation:

Harris Interactive® conducted a poll of American adults in August of 2011 to study the use of online medical information. Of the 1,019 randomly chosen adults, 60% had used the Internet within the past month to obtain medical information. Use the results of this survey to create an approximate 95% confidence interval estimate for the percentage of all American adults who have used the Internet to obtain medical information in the past month.

Answers

Answer:

[tex]0.60 - 1.96\sqrt{\frac{0.60(1-0.60)}{1019}}=0.570[/tex]

[tex]0.60 + 1.96\sqrt{\frac{0.60(1-0.60)}{1019}}=0.630[/tex]

The 95% confidence interval for the true proportion would be given by (0.570;0.630) .

And if we convert this into % we got (57.0%, 63.0%)

Step-by-step explanation:

The information given we have the following info given:

[tex] n = 1019[/tex] represent the sampel size

[tex] \hat p=0.6[/tex] represent the sample proportion of interest

The confidence level is 95%, our significance level would be given by [tex]\alpha=1-0.95=0.05[/tex] and [tex]\alpha/2 =0.025[/tex]. And the critical value would be given by:

[tex]z_{\alpha/2}=-1.96, z_{1-\alpha/2}=1.96[/tex]

The confidence interval for the mean is given by the following formula:  

[tex]\hat p \pm z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}[/tex]

Replacing the info given we got:

[tex]0.60 - 1.96\sqrt{\frac{0.60(1-0.60)}{1019}}=0.570[/tex]

[tex]0.60 + 1.96\sqrt{\frac{0.60(1-0.60)}{1019}}=0.630[/tex]

The 95% confidence interval for the true proportion would be given by (0.570;0.630) .

And if we convert this into % we got (57.0%, 63.0%)

Please help ASAP! Will give BRAINLIEST! Please read the question THEN answer correctly! No guessing.

Answers

The answer would be d and e (-3 and -5) two solutions because it is a quadratic with two real roots and the working out is shown in the photo.

40/50 to a simpel fraction

Answers

Answer:

4/5

Step-by-step explanation:

just divide by 10 since that's the largest number that both numbers can equally be divisible by

Answer:

4/5 because 40/50 simplified is 4/5 bc you knock off the zeros for question like that

Step-by-step explanation:

tell me the answer to the question plz​

Answers

Step-by-step explanation:

(11.99+23.98+9.95)= 45.92

she has to pay = 45.92 - 20/100 (45.92)

= 45.92 - 9.18 = 36.74

so option

about 37 is right

y = -16x2 + 242x + 78

Answers

Answer:

y=210x+78

Step-by-step explanation:

y=-16x*2+242x+78

y=-32x+242x+78

y=210x+78

Solve for I.
3x -8 < 23 AND
- 4x + 26 > 6

Answers

3x - 8 < 23
3x < 31
x = 31/3
-4x + 26 > 6
-4x > -20
x < 5


please answer this correctly I have to finish this today as soon as possible

Estimate the measure of this angle within 10°.

Answers

Answer:

It seems like it is 110 degrees.

Step-by-step explanation:

Will mark brainlist and give extra points bth grade math

Answers

Answer:

the answer is d

Step-by-step explanation:

Answer:

The answer is D

Step-by-step explanation:

What statement accurately describes the scatter point?
A. There are three distinct clusters.
B. There are no outliers.
C. There is one outlier.
D. There are two outliers.

Answers

D- there are two outliers

What is volume of a cylinder with base area 64pi cm² and a height equal to twice the radius? Give your answer in terms of pi.
512 pi
256 pi
1024 pi
4096 pi​

Answers

Answer:

  1024 pi

Step-by-step explanation:

The area formula is ...

  A = πr^2

So, the radius is ...

  r = √(A/π)

For the given area, the radius of the cylinder is ...

  r = √(64π/π) = 8 . . . . cm

The height is said to be twice this value, so is 16 cm.

__

The volume of the cylinder is found from ...

  V = Bh

where B is the base area and h is the height. Our cylinder has a volume of ...

  V = (64π cm^2)(16 cm) = 1024π cm^3

PI is the _ of a circle's _ to its _

Answers

Answer:

ratiocircumferencediameter

Step-by-step explanation:

Pi is the ratio of a circle's circumference to its diameter.

_____

We suspect you have answer choices for filling in these blanks. Besides the words shown above, there are other ways they can be filled:

  Pi is the ratio of a circle's area to its radius squared.

  Pi is the measure of a circle's central angle to its diameter endpoints.

Giving brainliest to CORRECT answer.

Answers

Answer:

D

If you put the equation into a calculator, it will show a graph of it.

Express this number in scientific notation 0.0008235

Answers

8.235*10^-4

= 0.0008235

Write the expanded form of h(3k-12.4)

Answers

Answer:3hk - 12.4h

Step-by-step explanation:

h(3k-12.4)

h x 3k - h x 12.4

3hk - 12.4h

Which types of triangles can be formed by taking the cross-section of a rectangular prism like the one shown above?

Answers

Answer: Equilateral, isosceles and scalene.

Step-by-step explanation:

A circle with circumference 8 has an arc with a 288 central angle what is the length of the arc

Answers

Answer:3.3

Step-by-step explanation:

Circumference=8

Φ=288

π=3.14

Radius=r

Circumference=2 x π x r

8=2 x 3.14 x r

8=6.28 x r

Divide both sides by 6.28

8/6.28=(6.28 x r) /6.28

1.3=r

r=1.3

Length of arc =Φ/360 x 2 x π x r

Length of arc =288/360 x 3.14 x 1.3

Length of arc =0.8 x 3.14 x 1.3

Length of arc =3.3

Answer:32/5

Step-by-step explanation: did it in khan

Simplify.
2567 · 162

Answers

Answer:

151 * 17 * 3^4 * 2

Step-by-step explanation:

2567 | 17

151 | 151

1

162 | 2

81 | 3

27 | 3

9 | 3

3 | 3

1

Answer:

415854.

Step-by-step explanation:

A multiplication.

Using a calculator it is:

415854,

ivana has 5.50 luc has 1.4 times as much as ivana, how many indian rupees would ivana get if the value of rupees are 61.92 per dollar rate

Answers

i think it would be 24.67 dollars because thats what i calculated but i dont know

The value of a car with an initial purchase price of $18,250 depreciates by

11% per year.

Answers

Step-by-step explanation:

This problem on depreciation of price.

Given data

initial price = $18,250

rate of depreciation = 11%

to solve for the new price we must find 11 percent of the initial price (depreciated value) and subtract from the initial price, we have

depreciation=

[tex]\frac{11}{100} *18250\\0.11*18250= 2007.5[/tex]

Hence the depreciation= $2007.50

the new amount is [tex]= initial amount - depreciation[/tex]

[tex]=18250-2007.50\\= 16242.50[/tex]

the new amount is $16242.50

Is p = –11 a solution to the inequality below?

p
> –5

Answers

Answer:

not a solution

Step-by-step explanation:

p > -5

Let p = -11

-11 > -5

This is a false statement

It is not a solution

When plotting points on the coordinate plane below, which point would lie on the y-axis?
(0, 1)
(7, 0)
(6, 8)
(8, 2)

Answers

1, 0 , 8, and 2 would all lie on the y-axis

Answer:

(0,1)

Step-by-step explanation:

i got it right

Two angles are supplementary. The measure of the larger angle is 12 degrees more than three times the smaller angle. Find the measures of the angles

Answers

Answer:

Measure of first angle: 42 degrees,

Measure of second angle: 138 degrees

Step-by-step explanation:

Let us say x ⇒ measure of the smaller angle, y ⇒ measure of the larger angle

1. Now given that the measure of the larger angle is 12° more than 3 times the smaller angle: y = 12 + 3x

2. If these angles are supplementary, we could formulate another equation were the two angles add to 180°: x + y = 180

3. In this situation it is convenient to apply substitution as to solve for x, y:

1. x + ( 12 + 3x ) = 180

2. x + 12 + 3x = 180

3. 4x + 12 + 180

4. 4x = 168

5. x = 42 degrees

4. Now substitute this value of x into the first equation y = 12 + 3x, and to solve for y as well:

1. y = 12 + 3 ( 42 )

2. y = 12 + 126

3. y = 138 degrees

Here we need to find two angles given that the angles are supplementary and one is 12° larger than the other.

the two angles are 84° and 96°.

We should start by defining what supplementary angles are.

Two angles a and b are supplementary if:

a + b = 180°.

Now, we also know that one of the angles is 12° larger than the other, so we can write:

a = b + 12°

Now that we have that equation, we can replace it in the first one, so we get:

a + b = 180°

(b + 12°) + b = 180°

Now we can solve this for b.

2*b + 12° = 180°

2*b = 180° - 12°  = 168°

b = 168°/2 = 84°

To find the value of a, we can use the equation:

a = b + 12°

a = 84° + 12° = 96°.

Then the two angles are:

84° and 96°.

If you want to learn more, you can read:

https://brainly.com/question/18164299

Find the values of the variable y, for which:
the difference between the fractions y+12/y-4 and y/y+4 is equal to their product


Answers

Answer:

  y = 12

Step-by-step explanation:

Ordinarily, in math, when we say "the difference between ..." we mean the second listed item is subtracted from the first. (In English, we often mean "the positive difference between ..." so the order doesn't matter.)

We'll assume we are only interested in the case where the difference is in the order listed.

  [tex]\dfrac{y+12}{y-4}-\dfrac{y}{y+4}=\dfrac{y+12}{y-4}\cdot\dfrac{y}{y+4}\\\\\dfrac{(y+12)(y+4)-(y-4)(y)}{y^2-16}=\dfrac{(y+12)(y)}{y^2-16}\\\\0=\dfrac{y^2-8y-48}{y^2-16}=\dfrac{(y-12)(y+4)}{(y-4)(y+4)}=\dfrac{y-12}{y-4}\qquad\text{$y\ne -4$}\\\\\boxed{y=12}[/tex]

There is one solution.

_____

Comment on the solution

If you were to "clear fractions" by multiplying the equation by (y^2-16), you would also obtain the extraneous solution y=-4. That is why we did not solve it that way.

Select the closest answer. *
20 points
1. Find the surface area of a sphere with a radius of 4.2 centimeters.
A. 235.6 cm?
C. 121.4 cm
B. 310.3 cm
D. 221.7 cm
A
B
С
OD
Select the closest answer.

Answers

Answer:

D. 221.7 cm

Step-by-step explanation:

Surface area of a sphere is: [tex]SA=4\pi r^2[/tex]

'r' - radius

We are given the radius of 4.2 centimetres.

[tex]SA=4\pi 4.2^2\\4 * \pi * 4.2^2\\\rightarrow 4.2^2 =17.64\\\text {Using 3.14 for pi: }\\4 * 3.14 *17.64\\12.56*17.64\\\boxed {221.5584}[/tex]

221.5584 ≈ 221.6

The closest answer is Option D, therefore it should be the correct answer.

what sock price should the company set to earn a maximum profit

Answers

Answer:

10000000000000

Step-by-step explanation:

I do not know how to explain

There were 15 students running in a race. How many different arrangements of first, second, and third place are possible?

Answers

Answer:

The area 2730 possible arrangements of first, second, and third place.

Step-by-step explanation:

The order in which the students finish is important. For example A, B and C is a different finishing order(outcome) than B, A and C. So we use the permutations formula to solve this question.

Permutations formula:

The number of possible permutations of x elements from a set of n elements is given by the following formula:

[tex]P_{(n,x)} = \frac{n!}{(n-x)!}[/tex]

In this question:

3 from a set of 15. So

[tex]P_{(15,3)} = \frac{15!}{(15-3)!} = 2730[/tex]

The area 2730 possible arrangements of first, second, and third place.

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