Ahouse 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: (a) reject the null because the test statistic (-1.2) is < the critical value (1.) do not reject the null because the test statistic (-1.2) is > the critical value (-1.) reject the null because the test statistic (-1.7531) is < the critical value (-1.) do not reject the null because the test statistic (1.2) is > the critical value (-1.7531).