Children's fitness is assessed by finding the distance, in meters, that they can run in 6 minutes. Overall, this distance varies fairly normally, with mean 835 and standard deviation 111.
a. What is the standard deviation of sample mean for samples of size 9?
b. Report the interval centered at the mean that has a 95% probability of containing sample mean for random samples of size 9.
c. What is the probability that sample mean is less than 761 or greater than 909?