Suppose I am testing a new tennis ball launcher and have made some improvements. Before I began tinkering with it, the variance of the distance that the balls were launched was 35 feet2, and I am interested in testing if I have managed to reduce the variance. I launch 45 balls and calculate the sample variance to be 32.4 feet2. What would be the test statistic of this hypothesis test

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?