Question 49 Partially correct The U.S. Department of Agriculture (USDA) uses sample surveys to produce important economic estimates. One pilot study used samples of sales Mark 9.14 out across the USA from two different months to estimate average wheat prices. Here are the summary statistics, in dollars per bushel, for these two months: of 16.00 P Flag question Month n S July 50 $2.90 $0.40 September 40 $3.60 $0.20 b. What is the approximate standard error of the difference between the mean prices in the two months? Give four decimal places. (2 marks) 0.20 c. What is the centre of a 98% confidence interval for the difference between the mean prices in the two months? (1 mark) -0.7 d. What is the degree of the freedom associated with the difference between the mean prices in the two months? (1 mark) 39 e. What is the margin of error of a 98% confidence interval for the difference between the mean prices in the two months? Give three decimal places. (1 mark) 0.151