According to the Internal Revenue Service, the mean tax refund for the year 2014 was $2,800. Assume the standard deviation is $450 and that the amounts refunded follow a normal probability...

According to the Internal Revenue Service, the mean tax refund for the year 2014 was $2,800. Assume the standard deviation is $450 and that the amounts refunded follow a normal probability distribution.

a. What percent of the refunds are more than $3,100?
(Round the intermediate values to 2 decimal places. Round your answer to 2 decimal places.)

b. What percent of the refunds are more than $3,100 but less than $3,500?
(Round the intermediate values to 2 decimal places. Round your answer to 2 decimal places.)

c. What percent of the refunds are more than $2,250 but less than $3,500?
(Round the intermediate values to 2 decimal places. Round your answer to 2 decimal places.)