What price do farmers get for their watermelon crops? In the third week of July, a random sample of 42 farming regions gave a sample mean of x = $6.88 per 100 pounds of watermelon. Assume that 0' is known to be $1.92 per 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 (in dollars). What is the margin of error (in dollars}? (For each answer, enter a number. Round your answers to two decimal places.) lower limit .1 v limit $ margin of error $ m i (b) Find the sample size necessary for a 90% confidence level with maximal error of estimate E = 0.31 for the mean price per 100 pounds of watermelon. (Enter a number. Round up to the nearest whole number.) X 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 (in dollars). What is the margin of error (in dollars)? Hint: 1 ton is 2000 pounds. [For each answer, enter a number. Round your answers to two decimal places.) lower limit $ 1917.78 upper limit $ margin of error 146. 21 y