For numbers 9 to 11, The principal of Mapayapa Integrated National High School claimed that the average salary of their teachers is f24, 000 per month. A random sample of 15 teachers in the school has a mean of P23, 220, and a standard deviation of P400. 9. Identify the population mean. A. P24,000 В. Р23,220 С. Р400 D. 15 10. Identify the sample mean, A. P24,000 В. Р23,220 С. Р400 D. 15 · 11. In testing the principal's claim, can we use the t-distribution? A: Yes, because the population standard deviation is unknown, and the sample size is small. .B. Yes, because the sample standard deviation is small, and variance is unknown. C. No, because the population standard deviation is greater than the sample standard deviation D. No, because the sample size is too small for the given sample standard deviation.