What price do farmers get for their watermelon crops? In the third week of July, a random sample of42farming regions gave a sample mean ofx= $6.88per 100 pounds of watermelon. Assume thatis known to be$1.94per 100 pounds.

(a) Find a 90% confidence interval for the population mean price (per 100 pounds) that farmers in this region get for their watermelon crop. What is the margin of error? (Round your answers to two decimal places.)

lower limit$_____

upper limit$_____

margin of error$_____

(b) Find the sample size necessary for a 90% confidence level with maximal error of estimateE=0.25for the mean price per 100 pounds of watermelon. (Round up to the nearest whole number.)

______farming regions

(c) A farm brings 15 tons of watermelon to market. Find a 90% confidence interval for the population mean cash value of this crop. What is the margin of error?Hint:1 ton is 2000 pounds. (Round your answers to two decimal places.)

lower limit=$______

upper limit=$_____

margin of error=$_____