describe probability values for normal distribution.

The mean amount of gasoline as well as services charged by Key Refining Company credit customers is $70 per month. The distribution of amounts expended is approximately normal with a standard deviation of $10.

1) Compute the probability of selecting a credit card customer at random and finding the customer charged between $70 and $83 last month.

2) Compute the probability of customers charging between $57 and $83 per month.

3) Key Refining decided to send a special financing plan to charge account customers having the highest 10 percent of the money charges. describe what is the dividing point between the customers who receive the special plan and those who do not?