Question

A national publication reported that a college student living away from home spends, on average, no more than $15 per month on laundry. You believe this figure is too low and want to disprove this claim. To conduct the test, you randomly select 16 college students and ask them to keep track of the amount of money they spend during a given month for laundry. The sample produces an average expenditure on laundry of $18.39, with a population standard deviation of $3.57. Use these sample data to conduct the hypothesis test. Assume you are willing to take a 5% risk of making a Type I error and that spending on laundry per month is normally distributed in the population.

(Round your answer to 2 decimal places.)

The value of the test statistic is

Answer 1

Solution :

This is the LEFT tailed test .

The null and alternative hypothesis is ,

H0 :   = 15

Ha : < 15

Test statistic = z

= ( - ) / / n

= (18.39 - 15) / 3.57 / 16 = 3.80

The value of the test statistic is 3.80