^{3. A statistics practitioner randomly sampled 1 500 observations with a mean of 14 and standard deviation of 25. Test whether there is enough evidence to infer that the population mean is different from 15. Use = 0.01. 4. The bus owner claims that the average number of his trips is more than 45 per week. A random sample of 10 buses was selected and it was found that the average number of trips for that week was 40 and a variance was 4. Test at 5% level of significance whether the bus owner's claim is true.}