For humans, gestation periods are normally distributed with a mean of \(266\) days and a standard deviation of \(16\) days.

a. Use the technology of your choice to simulate \(2000\) samples of nine human gestation periods each.

b. Find the sample mean of each of the \(2000\) samples

c. Obtain the mean, the standard deviation and a histogram of the \(2000\) sample means.

d. Theoretically, what are the mean, standard deviation and distribution of all possible sample means for sample of sizes \(9\)?

e. Compare your results from (c) and (d).

Short Answer

Expert verified

Part a. Answers may vary.

Part b. Answers may vary.

Part c. Answers may vary.

Part d. \(\mu_{\bar{x}}=266\)

\(\sigma_{\bar{x}}=5.3333\)

Part e. The answers can vary

Step by step solution

01

Part a. Step 1. Given information

\(\mu=266\)

\(\sigma=16\)

\(n=9\)

02

Part a. Step 2. Explanation

The \(2000\) samples of nine human gestation periods each needs to be calculated

While using the R program, the following command can be used to create \(9\times2000=18000\) data values.

A<-rnorm(1800, 266, 16)\)

This will be result of the stated question.

03

Part b. Step 1. Explanation

Now, the sample mean of each of the sample calculated in part (a) needs to be calculated

While using the R program, the following command can be used to determine the mean of every sample.

for (i in 1:2000){

M[i]< -mean(a[9 \times (i-8)):(9 \times i)])

}

04

Part c. Step 1. Explanation

Next, it is needed to calculate the mean, standard deviation and histogram of the \(2000\) samples means calculated in part (b):

While using the R program, the following commands can be used to determine the required values:

mean(M)

sd(M)

hist(M)

After this, the mean comes out to be \(266.0248\) and the standard deviation comes out to be \(5.36694\). The graph is represented as per below:

05

Part d. Step 1. Explanation

\(\mu_{\bar{x}}=\mu=266\)

\(\sigma_{x}=\frac{\sigma}{\sqrt{n}}=\frac{16}{\sqrt{3}} \approx 5.3333\).

06

Part e. Step 1. Explanation

It can be noted that in part (c), the mean and standard deviation are little greater than the subsequent theoretical standard deviation and mean in the part (d),

However, both of values in both parts are pretty close to each other. The difference could ve because of sampling error.

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Most popular questions from this chapter

According to the U.S. Census Bureau publication Manufactured Housing Statistics, the mean price of new mobile homes is \(65,100. Assume a standard deviation of \)7200. Let x denoted the mean price of a sample of new mobile homes.

Part (a): For samples of size 50, find the mean and standard deviation of x. Interpret your results in words.

Part (b): Repeat part (a) with n=100.

Refer to Fig. 7.6on page 306 .

a. Why are the four graphs in Fig. 7.6(a) all centered at the same place?

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c. Why are the graphs in Fig. 7.6(a) bell shaped?

d. Why do the graphs in Figs. 7.6(b)and (c) become bell shaped as the sample size increases?

America's Riches. Each year, forbes magazine publishes a list of the richest people in the United States. As of September l6, 2013, the six richest Americans and their wealth (to the neatest billion dollars) are as shown in the following table. Consider these six people a population of interest.

(a) For sample size of 4construct a table similar to table 7.2 on page293.(There are 15 possible sample of size 4

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Part (b): For each of the possible sample sizes, construct a table similar to Table 7.2on the page 293and draw a dotplot for the sampling for the sampling distribution of the sample mean similar to Fig 7.1on page 293.

Part (c): Construct a graph similar to Fig 7.3and interpret your results.

Part (d): For each of the possible sample sizes, find the probability that the sample mean will equal the population mean.

Part (e): For each of the possible sample sizes, find the probability that the sampling error made in estimating the population mean by the sample mean will be0.5or less, that is, that the absolute value of the difference between the sample mean and the population mean is at most 0.5.

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