A past study claimed that adults in America spent an average of 18 hours a week on leisure activities. A researcher wanted to test this claim. She took a sample of 12 adults and asked them about the time they spend per week on leisure activities. Their responses (in hours) are as follows. 13.6 14.0 24.5 24.6 22.9 37.7 14.6 14.5 21.5 21.0 17.8 21.4 Assume that the times spent on leisure activities by all American adults are normally distributed. Using a 10% significance level, can you conclude that the average amount of time spent by American adults on leisure activities has changed? (Hint: First calculate the sample mean and the sample standard deviation for these data using the formulas learned in Sections 3.1.1 and 3.2.2 of Chapter 3. Then make the test of hypothesis about .)