A vinyl siding company claims that the mean time to install siding on a medium-size

A vinyl siding company claims that the mean time to install siding on a medium-size house is at most 20 hours with a standarddeviation 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. 

1) At the 0.05 significance level, can a claim be made that it takes longeron average than 20 hours to side a house?
2) State the null and alternate hypotheses
3) State the decision rule
4) Compute the value of the test statistic
5) Formulate the decision rule
6) What is your decision regarding the null hypothesis and interpret.