4 . A vinyl siding company claims that the mean time to install siding on a medium - size house is at most 20 hours with a standard deviation of 3 7 hours A random sample of 40 houses sided in the last three years has a mean installation time of 20. 8 hours , At the 605 significance level can a claim be made that it takes longer on average than 20 hours to side a house ? State the null and alternate hypotheses . How His b . State the decision rule C . Compute the value of the test statistic d Formulate the decision rule