3.1 In a study of distances travelled by buses before there is the first major engine failure, a sampling of 40 buses resulted in a mean of \( 96700 \mathrm{~km} \). Based on previous studies, it can be assumed that the population standard deviation is \( 37500 \mathrm{~km} \). Use a 0,01 significance level to test the manufacturer's claim that the mean distance travelled before a major engine failure is more than \( 90000 \mathrm{~km} \).
(7)