Nike's annual report says that the average American buys 6.5 pairs of sports shoes per year. Suppose a sample of 61 customers is surveyed and the population standard deviation of sports shoes...

Nike's annual report says that the average American buys 6.5 pairs of
sports shoes per year. Suppose a sample of 61 customers is surveyed and
the population standard deviation of sports shoes purchased per year is 2.1.
a. What is the standard error of the mean in this experiment?
b. What is the probability that the sample mean is between 6
and 7 pairs of sports shoes?
c. What is the probability that the difference between the
sample mean and the population mean is less than 0.35 pair?