Find the value of the constant a for which the polynomial x^3 + ax^2 -1 will have -1 as a root. (A root is a value of x such that the polynomial is equal to zero.)

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?