A boy throws a book with an initial vertical velocity of 12.8 feet per second from a height of 3.2 feet. Use the vertical motion model, h(t) = -16t^2 + vot + h0 to find time spent in the air​

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?