In a study of distances travelled by buses before the first major engine failure, a sampling of

Question:

In a study of distances travelled by buses before the first major engine failure, a sampling of 191 buses resulted in a mean of 154,700 km and a standard deviation of 60,000 km. At the 0.05 level of significance, test the manufacturer's claim that mean distance travelled before a major engine failure is more than 144,000 km.