1. The time to solve a puzzle is being measured for two groups, elderly (over 70) and kids (under 10). For the 120 adults tested it took an average time of 24 minutes with a standard deviation of 4 minutes to solve the puzzle. For the sample of 88 kids it took an average time of 22 minutes with a standard deviation of 5 minutes to solve the puzzle.

a) At the .05 level is there a difference in the average time between kids and adults to solve the puzzle? (p = .002)

b) Based on a) how do explain the 2 minute difference in average of the two groups? (11)

2. A car has a gas mileage listing of 28 miles per gallon. You take the car out on 56 trips and find the average gas mileage to be 25 with a standard deviation of 6 mpg.

a) At the .01 level is the car getting gas mileage less than expected? (p = 0)

b) True or false: natural variability is the reason for the change in gas mileage Answer: