The average measured verbal IQ (IQV) scores of children is 100. In a sample of 20 children, the average was 86.9. Assume the population is normally distributed, and the population standard deviation is 18.5.



a) Find the 98% confidence interval of the true mean IQV

b) If we were to ask for a minimum sample size for a 94% level of confidence, what would be the value for z-sub-c? Round to 2 decimal places.

c) How large a sample must be obtained to be 94% confident that the true mean IQV is within 2 points of the sample mean? Round appropriately for this problem.