8. A restaurant manager believes that the average time customers spend waiting for their food is 10 minutes. To test this hypothesis, the manager randomly selects a sample of 40 customers and records the amount of time each one spends waiting for their food. The sample mean is found to be 12 minutes with a standard deviation of 3 minutes. Test the hypothesis that the population mean is 10 minutes against the alternative hypothesis that it is not 10 minutes. Use a significance level of $\alpha = 0.05$. Also, consider the case where $\alpha = 0.1$. (10 marks)