The mean amount of gasoline and services charged by Key Refining Company credit customers is $70 per month. The distribution of amounts spent is approximately normal with a standard deviation of $10.
A) Compute the probability of selecting a credit card customer at random and finding the customer charged between $70 and $83.
B) Compute the probability of finding the customer charged between $82 and $92 last month.
C) Compute the probability of finding the customer charged between $57 and $83 last month.
D) Compute the probability of finding the customer charged less than $54?
E) Compute the probability of finding the customer charged more than $54?
F) Suppose Key Refining decided to send a special financial plan to charge account customers having the highest 10% of the money charges. What is the dividing point between the customers who receive the special plan and those who do not?