Question

9. With a previous contractor, the mean time to replace a streetlight was 3.2 days. A city councilwoman thinks that the new contractor is not getting the streetlights replaced as quickly. She selects a random sample of 12 streetlight service calls and performs a la Sample T-test. Is there enough evidence to support the councilwoman's belief? Use a=0.05 level of significance and the information below. (How did you arrive at your conclusion?) T-Test of the Mean Test of mu = 3.200 vs mu > 3.200 Variable Replace N 12 Mean 4.433 St Dev 2.148 0.036 SE Mean 0.620 1.99

Answer 1

Here we want to test

Ho : mu = 3.200 Vs H1 : mu > 3.200

Level of significance a = 0.05

P-value = 0.036

Decision rule : If p-value < alpha we reject the null hypothesis otherwise we fail to reject the null hypothesis

Our p-value = 0.036 < 0.05

Decision : reject the null hypothesis Ho

Conclusion : There is enough evidence to support the councilwoman's belief .