In a recent year, about two-thirds of US households purchased ground coffee. Consider the annual ground coffee expenditures for households purchasing ground coffee, assuming that these expenditures are approximately distributed as a normal random variable with a mean of $65.16 and a standard deviation of $10.00.

a. Find the probability that a household spent less than $35.00.

b. Find the probability that a household spent more than $60.00.

c. What proportion of the households spent between $40.00 and $50.00.

d. 99% of the households spent less than what amount?