Sandy works at a clothing store. She makes $6 per hour plus earns 10% commission on her sales. She worked 71 hours over the last two weeks and had a total of $2,186 in sales before taxes.

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?