Question

A house cleaning service claims that it can clean a four bedroom house in less than 2 hours. A sample of n = 16 houses is taken and the sample mean is found to be 1.97 hours and the sample standard deviation is found to be 0.1 hours. Using a 0.05 level of significance the correct conclusion is:

Select one:

a. reject the null because the test statistic (-1.2) is < the critical value (1.7531).

b. do not reject the null because the test statistic (-1.2) is > the critical value (-1.7531).

c. reject the null because the test statistic (-1.7531) is < the critical value (-1.2).

d. do not reject the null because the test statistic (1.2) is > the critical value (-1.7531).

Answer 1

H0: 2

Ha: < 2

Test statistics

t = ( - ) / ( S / sqrt(n) )

= (1.97 - 2) / (0.1 / sqrt(16) )

= -1.2

Critical value at 0.05 level with 15 df = -1.7531 (From T table)

Decision = do not reject the null because the test statistic (-1.2) is > the critical value (-1.7531)