Question

Shoe Size
12
6
11
13
8
9
8
8
9
9
11
5
10
8
7
7
11
9
9
9
12
8
8
8
12
9
11
8
11
8
13
5
9
8
11

We need to find the confidence interval for the SHOE SIZE variable. To do this, we need to find the mean and standard deviation with the Week 1 spreadsheet. Then we can the Week 5 spreadsheet to find the confidence interval. This does not need to be separated by males and females, rather one interval for the entire data set.

First, find the mean and standard deviation by copying the SHOE SIZE variable and pasting it into the Week 1 spreadsheet. Write down the mean and the sample standard deviation as well as the count. Open the Week 5 spreadsheet and type in the values needed in the green cells at the top to find the confidence interval.

1. Give and interpret the 95% confidence interval for the size of students’ shoes.

Change the confidence level to 99% to find the 99% confidence interval for the SHOE SIZE variable.

2. Give and interpret the 99% confidence interval for the size of students’ shoes.

3. Compare the 95% and 99% confidence intervals for the size of students’ shoes. Explain the difference between these intervals and why this difference occurs.

We need to find the confidence interval for the SHOE SIZE variable. To do this, we need to find the mean and standard deviation with the Week 1 spreadsheet. Then we can the Week 5 spreadsheet to find the confidence interval. This does not need to be separated by males and females, rather one interval for the entire data set. First, find the mean and standard deviation by copying the SHOE SIZE variable and pasting it into the Week 1 spreadsheet. Write down the mean and the sample standard deviation as well as the count. Open the Week 5 spreadsheet and type in the values needed in the green cells at the top to find the confidence interval. Give and interpret the 95% confidence interval for the size of students’ shoes. Change the confidence level to 99% to find the 99% confidence interval for the SHOE SIZE variable. Give and interpret the 99% confidence interval for the size of students’ shoes. Compare the 95% and 99% confidence intervals for the size of students’ shoes. Explain the difference between these intervals and why this difference occurs.

Answer 1

hii..here i used Column B from 4 to 38 for shoe size.Since n is greater then 30, therefore we can use normal distribution for critical values.Now we can sav that we are 95% sure that the average shoes size is is 8.4651 to 9.8 206.

similarly we are 99% confidence that the average shoe size is 8.2522 to 10.0335.

we can say that the 99% confidence interval has wider length of confidence intervalas 95% confidence interval. this is because 99% interval cover more area as compared to 95% interval in normal distribution curve.