Help? How do I do this.

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?

An incoming airplane is x miles due north from the control tower at an airport. a second incoming airplane is y miles due east of the same control tower. the shortest distance between the two airplanes is z miles. which of the following functions would best model the situation above?

Walter is to make cookies for a basketball tournament. he's made 15 cookies so far. his coach asked him to make at least 20 cookies but no more than 55. solve the inequality and interpret the solution. 20 ? x + 15 ? 55