Acell phone plan charges $15 per month for 300 text messages. the plan charges eight cents for each additional text message. you use 60 additional text this month. what is your bill for the month

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?