Preliminary Data Analyses Indicate That It Is Reasonable to Use $\bar { x }$

Essay

Preliminary data analyses indicate that it is reasonable to use a t-test to carry out the specified hypothesis test. Performthe t-test using the critical-value approach.
-In one state, the mean time served in prison by convicted burglars is 18.7 months. A researcher would like to perform a hypothesis test to determine whether the mean amount of time served by convicted burglars in her hometown is different from 18.7 months. She takes a random sample of 11 such cases from court files in her home town and finds that $\bar { x }$ = 21 months and s = 7 months. Use a 5% significance level to perform the test.