A motorboat can maintain a constant speed of 15 miles per hour relative to the water. The boat makes a trip upstream to a certain point in 57 minutes; the return trip takes 33 minutes. What is the speed of the​ current?

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?