What is the range of the relation a. {-4,-3,-2,-1,0,1,2,4} b.{-4,-2,0,2,4} c.{-4,4} d.{-3,-2,-1,0,1}

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?