Some one help me pls

Iknow its nothing to do with education, but what type of thing should i wrote here? ? : ) its for mcdonald's btw.

What is the circumference of the pie

1. according to the internal revenue service, the mean tax refund for the year 2007 was $2,708. assume the standard deviation is $650 and that the amounts refunded follow a normal probability distribution. a. what percent of the refunds are more than $3,000? b. what percent of the refunds are more than $3,000 but less than $4,000? c. what percent of the refunds are less than $2,000?