1. A study of the amount of time it takes a mechanic to rebuild the transmission for a 2005 Chevrolet Cavalier shows that the mean is 8.4 hours and the standard deviation is 1.8 hours.If 40 mechanics are randomly selected, and the sample mean is computed.Describe the distribution of such sample means.

A.Skewed to the right

B.Skewed to the left

C.Uniform Distribution

D.Normal Distribution

2.A study of the amount of time it takes a mechanic to rebuild the transmission for a 2005 Chevrolet Cavalier shows that the mean is 8.4 hours and the standard deviation is 1.8 hours.If 40 mechanics are randomly selected, and the sample mean is computed.What is the mean of all such sample means?

A.8.4 hours

B.4.8 hours

C.0.21 hours

3.A study of the amount of time it takes a mechanic to rebuild the transmission for a 2005 Chevrolet Cavalier shows that the mean is 8.4 hours and the standard deviation is 1.8 hours.If 40 mechanics are randomly selected, and the sample mean is computed.What is the standard deviation of all such sample means?

B.0.28 hour

B.6.3 hours

C.1.8 hours

4.The result of a bone density test is commonly measured as a z score, and the population of z scores is normally distributed with a mean of 0 and a standard deviation of 1.

What's the shape of the graph of the distribution of bone density test scores.

A.Skewed to the left

B.Skewed to the right

C.Bell-shaped