Mid-Term Exam

Question 1

The diameter of a brand Ping Pong ball is approximately normally distributed with a mean of 1.30 inches and a standard deviation of 0.04 inch. If you select a sample of 16 Ping Pong balls,

1. What is the sampling distribution of the mean?
2. What is the probability that the sample mean is less than 1.28 inches?
3. What is the probability that the sample mean is between 1.31 and 1.33 inches?
4. The probability is 60% is that the sample is between what two values symmetrically distributed around the population mean?

Question 2

If the manager of a paint supply store wants to estimate with 95% confidence the mean amount of paint in a 1-gallon can to within0.004 gallon and also assume that the standard deviation is 0.02 gallon, what is the sample size needed?

Question 3

The data below represent the calories and fat (in grams) of a 16-ounce iced drink at Dunkin' Donuts and Starbucks.

Product	Calories	Fat
Dunkin' Donuts Mocha Swirl Latte (whole milk)	240	8.0
Starbucks Coffee Frappuccino blended coffee	260	3.5
Dunkin' Donuts Coffee Coolatta (cream)	350	22.0
Starbucks Iced Coffee Mocha Expresso (whole milk and whipped cream)	350	20.0
Starbucks Mocha Frappuccino blended coffee (whipped cream)	420	16.0
Starbucks Coffee Brownie Frappuccino blended coffee (whipped cream)	510	22.0
Starbucks Chocolate Frappuccino Blended Crme (whipped cream)	530	19.0

1. Compute and interpret the coefficient of correlation r
2. At the 0.05 level of significance, is there is a significant association between calories and fat?

Question 4

The data shown below contain the overall miles per gallon (MPG) of a 2009 small SUVs priced under $30,000:

24 23 22 21 22 22 18 19 19 19 21 21 21 18 19 21 17 22 18 18 22 16 16

1. Construct a 95% confidence interval estimate for the population mean MPG of 2009 SUVs priced under $30,000, assuming a normal distribution.
2. Interpret the interval constructed in (a)