Answer:
the answer should be 158 but I'm not a hundred percent sure
Ms Davis is doing an activity with her statistic students where she gives them a 20 question multiple top choice test and they know none of the answers. Students need to guess on every question and each question has 5 possible choices, 1 of the which is correct.
What is the mean and standard deviation of the number of questions that each student gets correct?
Answer:
The mean and standard deviation of the number of questions that each student gets correct are 4 and 1.789 respectively.
Step-by-step explanation:
Let the random variable X be defined as the number of correct answers marked by a student.
It is provided that each question has 5 possible choices, 1 of the which is correct.
Then the probability of marking thee correct option is:
[tex]P(X)=\frac{1}{5}=0.20[/tex]
There are a total of n = 20 questions to be answered.
As the students does not the answer to any question, they would be guessing for each question. This implies that for a random question, all the five options has the equal probability of being correct and each of the five options can be correct independently from the other.
All these information above indicates that the random variable X follows a Binomial distribution with parameters n = 20 and p = 0.20.
The mean and standard deviation of a Binomial distribution are:
[tex]\mu=np\\\\\sigma=\sqrt{np(1-p)}[/tex]
Compute the mean and standard deviation of the random variable X as follows:
[tex]\mu=np=20\times 0.20=4\\\\\sigma=\sqrt{np(1-p)}=\sqrt{20\times 0.20\times(1-0.20)}=1.789[/tex]
Thus, the mean and standard deviation of the number of questions that each student gets correct are 4 and 1.789 respectively.
According to the question,
The probability of making 3 correct options will be:
→ [tex]P(X) = \frac{1}{5}[/tex]
[tex]= 0.20[/tex]
Total number of questions,
n = 20As we know,
The mean will be:
→ [tex]\mu = np[/tex]
By substituting the values, we get
[tex]= 20\times 0.20[/tex]
[tex]= 4[/tex]
and,
The standard deviation will be:
→ [tex]\sigma = \sqrt{np(1-p)}[/tex]
[tex]= \sqrt{20\times 0.20\times (1-0.20)}[/tex]
[tex]= 1.789[/tex]
Thus the responses above are correct.
Learn more about standard deviation here:
https://brainly.com/question/20896613
2. Inflation is at a rate of 7% per year. Evan's favorite bread now costs $1.79. What did it cost 10 years ago? How long
before the cost of the bread doubles?
Answer:
It cost $0.91 10 years ago.
It takes 10.24 years for the cost of bread to double.
Step-by-step explanation:
The equation for the price of bread after t years has the following format:
[tex]P(t) = P(0)(1+r)^{t}[/tex]
In which P(0) is the current price, and r is the inflation rate, as a decimal.
If we want to find the price for example, 10 years ago, we find P(-10).
Inflation is at a rate of 7% per year. Evan's favorite bread now costs $1.79.
This means that [tex]r = 0.07, P(0) = 1.79[/tex]. So
[tex]P(t) = P(0)(1+r)^{t}[/tex]
[tex]P(t) = 1.79(1+0.07)^{t}[/tex]
[tex]P(t) = 1.79(1.07)^{t}[/tex]
What did it cost 10 years ago?
[tex]P(-10) = 1.79(1.07)^{-10} = 0.91[/tex]
It cost $0.91 10 years ago.
How long before the cost of the bread doubles?
This is t for which P(t) = 2P(0) = 2*1.79. So
[tex]P(t) = 1.79(1.07)^{t}[/tex]
[tex]2*1.79 = 1.79(1.07)^{t}[/tex]
[tex](1.07)^{t} = 2[/tex]
[tex]\log{(1.07)^{t}} = \log{2}[/tex]
[tex]t\log{1.07} = \log{2}[/tex]
[tex]t = \frac{\log{2}}{\log{1.07}}[/tex]
[tex]t = 10.24[/tex]
It takes 10.24 years for the cost of bread to double.
A bag contains 10 Yellow, 4 Green and 7 Blue marbles. Find the following probabilies.
P(blue)
Answer:
1/3
Step-by-step explanation:
The total number of marbles
10+4+7 = 21
P(blue) = blue marbles / total marbles
= 7 / 21
= 1/3
Really need help on this. I keep gettin it wrong please help!!!
Answer:
1436.76 m³
Step-by-step explanation:
Volume of sphere= 4/3 π r ³
V= 4/3(3.14)(7)³
V=4/3(3.14)(343)
V= 4310.26 / 3
V= 1436.76 m³
Draw a quadrilateral that does not belong then explain why
Answer:
a kite
Step-by-step explanation:
I really need some HELP.............
Answer:
119000
Step-by-step explanation:
The median is the middle value when placed from smallest to largest
95000, 112000, 126000, 13000
The middle is between 112000 and 126000 so take the average
(112000+126000)/2 =238000/2 =119000
Rewrite the percentage in the sentence below as a decimal.
The 20 overseas investors own 7.2% of the business.
Answer:
0.072
Step-by-step explanation:
Answer:0.072
Step-by-step explanation:
7.2% = 7.2/100
7.2 ➗ 100=0.072
The corresponding sides of ΔABC and ΔDEF have equal lengths. The area of ΔABC is 4 square units, and the longest side of ΔDEF is 5 units long. What is the area of ΔDEF?
Answer:
4 square units
Step-by-step explanation:
If corresponding sides have equal lengths, the triangles are congruent by the SSS postulate. They must have equal areas: 4 square units.
ΔDEF has an area of 4 square units.
Answer:
if the corresponding sides are equal the 2 triangles are congruent ( by SSS) so their areas are the same.
So area of triangle DEF = 4 sq units
Step-by-step explanation:
Subtracting by adding up 65-39
Answer:
26Step-by-step explanation:
In order to subtract by adding up 65-39, we need to add -39 to the value of 65. This can be rewritten in this way;
65+(-39)
The equation above is similar to the one given because the product of a minus and a plus sign will still give us back a minus sign.
on solving;
65+(-39) = 26
55 POINTS IF YOU GET RIGHT THEN GOATED AND BRAINIEST!!
Answer:
17 i would say it is D
18 i belive it is B
19 it is c
20 A
Carpetland carpet installers incur an average cost of $300 for each carpet installed. Joan Chin, the firm’s vice president, proposes a new procedure for installations, which she hopes will be more efficient. Joan plans to run a trial and hopes that the results of a trial period will enable her to conclude with a level of significance of 0.05 that the new procedure reduces the average cost to install a carpet. If Joan's hypothesis test results in a Type II error, what would this mean?
Answer:
A Type II error happens when the null hypothesis failed to be rejected, although it is false and the alternative hypothesis is true.
In this context, would be that the test does not give enough evidence to support the claim that the new procedure reduces the average cost, although it really does reduces it.
The new procedure is effective, but the sample does not give enough evidence.
Step-by-step explanation:
Find the surface area of the pyramid to the nearest whole number.
Answer:
i think its 248m^2
Step-by-step explanation:
Find the greatest common factor of the
following monomials:
34c3 2c5
Answer:2c^2
Step-by-step explanation:
34c^3 and 2c^5
34c^3=2 x 16 x c x c^2
2c^5=2 x c^2 x c^3
Greatest common factor =2 x c^2
Greatest common factor =2c^2
-5(4x + 7) <25
Answer here
Answer:
X>-3
Step-by-step explanation:
Hope I helped
Do u want the steps ?
Answer: x > -3
Step-by-step explanation: -5(4x + 7) <25
-20x - 35 < 25
-20x -35 + 35 < 25 + 35
-20x/20 < 60/20
x > -3
Daniel believes that people perform better in the barbell curl, on average, if they are encouraged by a coach. He recruited 29 subjects to participate in an experiment and randomly assigned them into two groups. Daniel gave one group verbal encouragement during the exercise and was quiet during the exercise for the other group. He recorded the total number of barbell curls each subject was able to complete before setting the bar down.
Explain the purpose of random assignment in this experiment.
Answer:
Define two roughly identical sets.
Reduce the chance of bias.
Step-by-step explanation:
In this experiment, Daniel performs a random assignment in order to stablish two separate groups with roughly equivalent ability to do barbell curls. Two different treatments (verbal encouragement and silence) are then applied in order to verify for a cause and effect relationship. If the groups were not randomly assigned, then the experiment could be biased.
Gibbs Baby Food Company wishes to compare the weight gain of infants using its brand versus its competitor’s. A sample of 40 babies using the Gibbs products revealed a mean weight gain of 7.6 pounds in the first three months after birth. For the Gibbs brand, the population standard deviation of the sample is 2.3 pounds. A sample of 55 babies using the competitor’s brand revealed a mean increase in weight of 8.1 pounds. The population standard deviation is 2.9 pounds. At the .05 significance level, can we con- clude that babies using the Gibbs brand gained less weight? Compute the p-value and interpret it.
Answer:
[tex]z=\frac{(7.6-8.1)-0}{\sqrt{\frac{2.3^2}{40}+\frac{2.9^2}{55}}}}=-0.936[/tex]
The p value can be founded with this formula:
[tex]p_v =P(z<-0.936)=0.175[/tex]
Since the p value is higher than the significance level provided of 0.05 we have enough evidence to FAIL to reject the null hypothesis and we can't conclude that the true mean for the Gibbs brand is significantly lower than the true mean for the competitor
Step-by-step explanation:
Information given
[tex]\bar X_{1}=7.6[/tex] represent the mean for Gibbs products
[tex]\bar X_{2}=8.1[/tex] represent the mean for the competitor
[tex]\sigma_{1}=2.3[/tex] represent the population standard deviation for Gibbs
[tex]\sigma_{2}=2.9[/tex] represent the sample standard deviation for the competitor
[tex]n_{1}=40[/tex] sample size for the group Gibbs
[tex]n_{2}=55[/tex] sample size for the group competitor
[tex]\alpha=0.05[/tex] Significance level provided
z would represent the statistic
Hypothesis to verify
We want to check if babies using the Gibbs brand gained less weight, the system of hypothesis would be:
Null hypothesis:[tex]\mu_{1}-\mu_{2}=0[/tex]
Alternative hypothesis:[tex]\mu_{1} - \mu_{2}< 0[/tex]
The statistic would be given by:
[tex]z=\frac{(\bar X_{1}-\bar X_{2})-\Delta}{\sqrt{\frac{\sigma^2_{1}}{n_{1}}+\frac{\sigma^2_{2}}{n_{2}}}}[/tex] (1)
Replacing the info given we got:
[tex]z=\frac{(7.6-8.1)-0}{\sqrt{\frac{2.3^2}{40}+\frac{2.9^2}{55}}}}=-0.936[/tex]
The p value can be founded with this formula:
[tex]p_v =P(z<-0.936)=0.175[/tex]
Since the p value is higher than the significance level provided of 0.05 we have enough evidence to FAIL to reject the null hypothesis and we can't conclude that the true mean for the Gibbs brand is significantly lower than the true mean for the competitor
If you roll a die three times, what is the probability of rolling three ONES?
(Give your answer as a decimal, rounded to the nearest thousandth. That is, rounded to three decimal places.)
Answer:
0.004
Step-by-step explanation:
The probability of rolling any number is 1/6 so that times 3 is 1/216 that as a decimal i 0.004
Write the sentence as a proportion: $3.50 for 9 bottles is equivalent to $31.50 for 81 bottles.
Answer:
$0.39:1
Step-by-step explanation:
$0.39:1
Dividing the amount by the cost of the bottles.
The sum of the measures of the angles of a triangle is 180. The sum of the measures of the second and third angles is five times the measure of the first angle. The third angle is 14 more than the second. Let x, y, and z represent the measures of the first, second, and third angles, respectively. Find the measures of the three angles.
Answer:
[tex]x=30\\y=68\\z=82[/tex]
Step-by-step explanation:
x = measure of the first angle
y = measure of the second angle
z = measure of the third angle
The sum of the measures of the second and third (y+z) is five times the measure of the first angle (=5x)
[tex]y+z=5x[/tex]
The third angle is 14 more than the second
[tex]z=y+14[/tex]
And remember that the sum of these three angles must be equal to 180.
[tex]x+y+z=180[/tex]
Let's take these equations
[tex]y+z=5x\\z=y+14\\x+y+z=180[/tex]
If you take a look at the first equation, we have y+z = 5x and we have y+z in the third equation as well, we can replace that....
[tex]x+y+z=180\\x+(y+z)=180\\x+(5x)=180[/tex]
Distribute the + sign
[tex]x+5x=180[/tex]
Combine like terms;
[tex]6x=180[/tex]
Divide by 6.
[tex]x=\frac{180}{6}\\ x=30[/tex]
We have now defined that the measure of the first angle is 30º.
Let's take another equation... for example [tex]z=y+14[/tex]
I'm going to take this one because if I replace x and z in the third equation, all I'll have left will be y.
[tex]x+y+z=180\\30+y+(y+14)=180[/tex]
Distribute the + sign and Combine like terms;
[tex]30+y+y+14=180\\44+2y=180\\[/tex]
Subtract 44 to isolate 2y.
[tex]2y=180-44\\2y=136[/tex]
Now divide by 2.
[tex]y=\frac{136}{2}\\ y=68[/tex]
We already have the value of x and y. Once again, replacing this in the third equation will leave us with z to solve for.
[tex]x+y+z=180\\30+68+z=180\\98+z=180\\z=180-98\\z=82[/tex]
Write parametric equations of the line 2x - y = 3.
a. X = 1, y = 2t - 2
c.
X = 1, y = 3t-2
b. X= 1, y = 2t-3
d.
1
1
X = 1,y= =
2
1.9 -
3
Please select the best answer from the choices provided
A
OB
С
OD
What parallelogram has a base of 2 units and a height of 4 units
Answer:
C
Step-by-step explanation:
The parallelogram in C has a base of 2 units and a height o 4 units.
For the inverse variation equation xy = k, what is the constant of variation, k, when x = 7 and y = 3?
Answer:
k=21
Step-by-step explanation:
x=7 X y=3 = 21
7 x 3 = 21
Answer:21
Step-by-step explanation:
xy=k
k=xy x=7 y=3
k=7 x 3
k=21
Please help ASAP! I will mark Brainliest! Please READ the question THEN answer CORRECTLY! No guessing!
Answer:
C. [tex]\frac{\sqrt{5} }{8}[/tex]
Step-by-step explanation:
This expression can be rewritten as [tex]\frac{\sqrt{5} }{\sqrt{64} }[/tex].
Since the square root of 5 is prime and does not have any perfect square factors, it cannot be simplified. However, the square root of 64 is equal to 8, so our final simplified radical expression would be [tex]\frac{\sqrt{5} }{8}[/tex], which is option C.
HOPE THIS HELPED! :)
Answer:
C is the answer
Step-by-step explanation:
You have to rewrite as [tex]\sqrt{5}[/tex]/[tex]\sqrt{64}[/tex]. Then you have to simplify the denominator which is 8. That is how you get your answer.
Hope this helps.
Simplify the radical below.
Square root 84
A. 221
B. 242
C. 4.21
D. 4.42
Pls no explanation will give you 20 points in in a hurry
the answer is B
Step-by-step explanation:
and I would love 20 points
Points X( -6, -4), Y( -2, -8), Z( 2,-4) are the vertices of a right triangle. What is the area of XYZ? Round to the nearest tenth.
Answer:
16
Step-by-step explanation:
distance between point x and z is 8 units
distance between point z and y is 4 units
8 * 4 = 32
formula for area of a triangle (l * w)/2
plugin: (8 * 4)/2 = 16
How many boys are there in an introductory geology course if 360 students are enrolled and there are five boys to every seven girls?
Answer:150 branliest
Step-by-step explanation:
Answer:
150
Step-by-step explanation:
360/(5+7)=30
30*5=150
the midpoint of AB is point P at (-16,6) if point A is at (-10,8) what are the coordinates of point B?
Answer:
Denote B(x, y), we have:
-10 + x = 2 x (-16) => x = -22
8 + y = 2 x 6 => y = 4
=> B(-22, 4)
Hope this helps!
:)
To measure the height of the cloud cover at an airport, a worker shines a spotlight upward at an angle 75° from the horizontal. an observer at a distance d = 560 m away measures the angle of elevation to the spot of light to be 45°. find the height h of the cloud cover,
Answer:
The height of the cloud cover is 441.66 meters
Step-by-step explanation:
Distance = 560 m
The height of the cloud cover = h meters
According to the diagram, the worker stands at point R,
Let RT = x
tan 45⁰ = [tex]\frac{opposite}{adjacent}[/tex] = [tex]\frac{h}{x}[/tex]
therefore, 1 = [tex]\frac{h}{x}[/tex], h = x
Then tan 75⁰ = [tex]\frac{h}{560-x}[/tex], substituting x = h, we have
3.732 = [tex]\frac{h}{560-h}[/tex]
3.732(560 - h) = h
3.732 × 560 = 3.732h + h
2089.92 = 4.732h
h = 441.66 m
The height of the cloud cover is 228.62 meters
The given parameters are:
[tex]\mathbf{\alpha = 75^o}[/tex]
[tex]\mathbf{\theta = 45^o}[/tex]
[tex]\mathbf{d = 560m}[/tex]
See attachment for the image of the cloud cover.
From the attached image, we have the following sine ratios:
[tex]\mathbf{sin(75) = \frac hx}[/tex]
[tex]\mathbf{sin(45) = \frac h{560 - x}}[/tex]
Make h the subject in both equations
[tex]\mathbf{ h = xsin(75)}[/tex]
[tex]\mathbf{ h = (560 - x) sin(45)}[/tex]
So, we have:
[tex]\mathbf{ xsin(75) = (560 - x) sin(45)}[/tex]
Open brackets
[tex]\mathbf{ xsin(75) = 560sin(45) - x sin(45)}[/tex]
Collect like terms
[tex]\mathbf{ xsin(75) + x sin(45)= 560sin(45) }[/tex]
Evaluate sine 45 and 75
[tex]\mathbf{ 0.9659x + 0.7071x= 560 \times 0.7071}[/tex]
[tex]\mathbf{ 1.673x= 395.976}[/tex]
Divide both sides by 1.673
[tex]\mathbf{ x= 236.69}[/tex]
Recall that:
[tex]\mathbf{ h = xsin(75)}[/tex]
So, we have:
[tex]\mathbf{h = 236.69 \times 0.9659}[/tex]
[tex]\mathbf{h = 228.618871}[/tex]
Approximate
[tex]\mathbf{h = 228.62}[/tex]
Hence, the height of the cloud cover is 228.62 meters
Read more at:
https://brainly.com/question/16979479
Employees at a manufacturing plant have seen production
rates change by approximately 105% annually. In contrast,
the graph shows the change in the average annual wages
of the employees
Which statement accurately compares the annual change
in production to the annual change in average salary?
50.000
50.000
0 The annual changes cannot be compared because the
initial production value is unknown.
The annual change in production will, at some point,
exceed the annual change in average salary
The annual change in production increases at a slower
rate, 5% per year, than the annual increase in the
average salary, $500 per year.
The annual change in production increases at a slower
rate, 105% per year, than the annual increase in average
salary, $500 per year
40
30.000
20.000
10.000
Answer:
both measures show strong growth in CEO
Step-by-step explanation:
350 firms in 2018 was $17.2 million- or $14.0 both show that they have a strong growth in the last 2 years.
Answer:
The answer is B "The annual change in production has exceeded the annual change in the average salary."
Step-by-step explanation:
Yes
Please help ASAP! I will mark Brainliest! Please answer CORRECTLY! No guessing!
Answer:
Option D: 5591.93
Step-by-step explanation:
The best way to understand this question is to apply the formula in an indirect manner;
P - Principle number, Starting Value
T - Time
I - Interest
Let us convert the interest into decimal form, such that 3.8% is shifted two decimal points to the right ⇒ 0.038. Now add 1 to this value to get ⇒ 1.038. By PEDMAS, you would first raise this value to the span of 3 years as such:
(1.038)^3 = 1.118386872.......
The final step would by to multiply the starting value (investment $) $ 5,000 by this continuing value of 1.118386872:
5,000(1.118386872) = 5591.93436 ⇒ Rounded to (About) 5591.93
Answer:D
Step-by-step explanation:
principal=p=$5000
Rate=r=3.8%
Time=n=3 years
amount=a
a=p(1+r/100)^n
a=5000(1+3.8/100)^3
a=5000(1+0.038)^3
a=5000(1.038)^3
a=5000 x 1.038 x 1.038 x 1.038
a=5591.93
a=$5591.93