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Tall girls? To see if the claim made in Exercise 12is true at their high school, an Ap Statistics class chooses an SRS of twenty 16-year-old females at the school and measures their heights. In their sample, the mean height is 64.7inches. Does this provide convincing evidence that 16-year-old females at this school are taller than 64inches, on average?

a. What is the evidence that the average height of all 16-year-old females at this school is greater than 64inches, on average?

b. Provide two explanations for the evidence described in part (a).

We used technology to simulate choosing 250SRSs of size n=20from a population of three hundred 16-year-old females whose heights follow a Normal distribution with mean localid="1654113150676" μ=64inches and standard deviation μ=2.5inches. The dotplot shows x=the sample mean height for each of the 250simulated samples.

c. There is one dot on the graph at 62.5. Explain what this value represents.

d. Would it be surprising to get a sample mean of x=64.7or larger in an SRS of size 20when μ=64inches and σ=2.5inches? Justify your answer.

e. Based on your previous answers, is there convincing evidence that the average height of all 16-year-old females at this school is greater than 64inches? Explain your reasoning.

Short Answer

Expert verified

(a) The 64.7inchesis the sample mean, which is larger than data-custom-editor="chemistry" 64inches.

(b) It's also feasible that the sample mean is bigger than 64inches because the population's average height is higher.

(c) One simple random sample of twenty females aged sixteen years old, with a mean height of data-custom-editor="chemistry" 62.5inches.

(d) No, it is not surprising to get the given sample mean.

(e) No, there is no convincing evidence for the average height.

Step by step solution

01

Part (a) Step 1: Given information

We need to find the evidence for an average height of females.

02

Part (a) Step 2: Explanation

We know that

Sample mean is,x¯=64.7

Therefore, The sample mean of 64.7inches, which is greater than 64inches, is proof that the "average height of all 16-year-old females at this school is greater than 64inches, on average."

03

Part (b) Step 1: Given information

We need to find the explanations for the evidence described in part (a).

04

Part (b) Step 2: Explanation

Because the population mean height is 64inches and we got a sample with a sample mean of 64.7inches by chance, it's feasible that the sample mean is more than 64inches.

However, it's also feasible that the sample mean is bigger than 64inches because the population's average height is higher.

05

Part (c) Step 1: Given information

We need to find the representation of value 62.5.

06

Part (c) Step 2: Explanation

Each dot in the dotplot indicates a sample mean xfor a simple random sample (SRS) of twenty 16-year-old females, where the sample mean is the sample's average height.

The 62.5-inch dot indicates a simple random sample of twenty 16-year-old females with a sample mean height of 62.5inches.

07

Part (d) Step 1: Given information

We need to find out whether the value sample mean is surprising or not.

08

Part (d) Step 2: Explanation

In the above dotplot, there are 11 dots above 64.7 inches and several dots to the right of 64.7 inches. When the population mean is 64 inches, this means that a sample mean of at least 64.7 inches is very likely to be obtained. As a result, a sample mean of 64.7 or higher is not uncommon.

09

Part (e) Step 1: Given information

We need to find the convincing evidence for the part (d).

10

Part (e) Step 2: Explanation

From part (d)

We know that

It is not surprising to get the sample mean greater than or equal to the given sample mean.

Which means that there is no persuasive evidence that all 16-year-old females at this school are taller than 64inches.

Therefore, there is no evidence.

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