6. Each member of a random sample of 15 business economists was asked to
predict the rate of in‡ation for the coming year. Assume that the predictions
for the whole population of business economists follow a normal distribution
with standard deviation 1.8%.
a. The probability is 0.01 that the sample standard deviation is bigger than
b. The probability is 0.025 that the sample standard deviation is smaller
than what number?
c. Find any pair of numbers such that the probability that the sample stan-
dard deviation lies between these numbers is 0.90.
I am not sure how to do this. I feel like I am missing a piece of information but I am not.