Question: In a recent year the fuel economy of all passenger vehicles was 19.8 mpg. A trade organization sampled 50 passenger vehicles for fuel economy and obtained a sample mean of 20.1 mpg with standard deviation 2.45 mpg. The sample mean 20.1 exceeds 19.8, but perhaps the increase is only a result of sampling error.
a. Perform the relevant test of hypotheses at the 20% level of significance using the critical value approach.
b. Compute the observed significance of the test.
c. Perform the test at the 20% level of significance using the p-value approach. You need not repeat the first three steps, already done in part (a).