A water tank is a cylinder with radius 40 cm and depth 150 m

An investor is interested in purchasing an apartment building containing six apartments. The current owner provides the followin

Vsevolod [243]

Answer:

b) 2.7632

Step-by-step explanation:

To find the mean, we multiply each value by it's probability. So

$E = 0\frac{5}{38} + 1\frac{9}{38} + 2\frac{7}{38} + 3\frac{4}{38} + 4\frac{3}{38} + 5\frac{2}{38} + 6\frac{8}{38} = \frac{1*9 + 2*7 + 3*4 + 4*3 + 5*2 + 6*8}{38} = 2.7632$

So the correct answer is:

b) 2.7632

4 0

2 years ago

Read 2 more answers

What is the equation of the graph below? On a coordinate plane, a curve goes through (0, 0). It has a maximum of 1 and a minimum

bogdanovich [222]

Answer:

y=cos(x+π)

Step-by-step explanation:

Known that the cosine function has a period of 2π.

Now, the parental function is y = cosx, which has y-intercept at y = 1, and x-intercept at π/2.

Notice that the function showed in the graph attached has y-intercept at y = -1 and x-intercept at π/2. This indicates that the function has been moved leftwards π units.

Therefore, the function that belongs to this graph is

$y=cos(x + \pi)$

6 0

2 years ago

A small school with 60 total students records how many of their students attend on each of the 180 days in a school year. the ma

horrorfan [7]

Answer:

For the sampling distribution,

a) Mean = μₓ = 55.0 students.

b) Standard Deviation = 1.8 students.

Step-by-step explanation:

The complete Question is attached to this solution.

The Central limit theorem explains that for the sampling distribution, the mean is approximately equal to the population mean and the standard deviation of the sampling distribution is related to the population standard deviation through

σₓ = (σ/√n)

where σ = population standard deviation = 4

n = sample size = 5

Mean = population mean

μₓ = μ = 55 students.

Standard deviation

σₓ = (σ/√n) = (4/√5) = 1.789 students = 1.8 students to 1 d.p

Hope this Helps!!!

5 0

2 years ago

It is believed that as many as 23% of adults over 50 never graduated from high school. We wish to see if this percentage is the

JulijaS [17]

Answer:

1) n=48

2) n=298

3) n=426

Step-by-step explanation:

Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

$p$ represent the real population proportion of interest

$\hat p$ represent the estimated proportion for the sample

n is the sample size required (variable of interest)

$z$ represent the critical value for the margin of error

The population proportion have the following distribution

$p \sim N(p,\sqrt{\frac{\hat p(1-\hat p)}{n}})$

Part 1

In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 90% of confidence, our significance level would be given by $\alpha=1-0.90=0.10$ and $\alpha/2 =0.05$ . And the critical value would be given by:

$z_{\alpha/2}=-1.64, z_{1-\alpha/2}=1.64$

The margin of error for the proportion interval is given by this formula:

$ME=z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}$ (a)

And on this case we have that $ME =\pm 0.1$ and we are interested in order to find the value of n, if we solve n from equation (a) we got:

$n=\frac{\hat p (1-\hat p)}{(\frac{ME}{z})^2}$ (b)

We can assume that the estimated proportion is 0.23 for the 25 to 30 group. And replacing into equation (b) the values from part a we got:

$n=\frac{0.23(1-0.23)}{(\frac{0.1}{1.64})^2}=47.63$

And rounded up we have that n=48

Part 2

The margin of error on this case changes to 0.04 so if we use the same formula but changing the value for ME we got:

$n=\frac{0.23(1-0.23)}{(\frac{0.04}{1.64})^2}=297.7$

And rounded up we have that n=298

Part 3

In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 95% of confidence, our significance level would be given by $\alpha=1-0.95=0.05$ and $\alpha/2 =0.025$ . And the critical value would be given by: