:Income from different car companies is to be estimated for 2010 from a sample of 6 of the 19 car companies that reported figures early for that year. Incomes from all 19 car companies are known for 2000 and the total is $674 billion. From the data provided, estimate the total income from car companies in 2010, with a bound on the error. All figures are in billions of dollars. Company 2000 2010 Nissan 21 26 BMW 63 91 Audi 91 47 Toyota 60 70 Ford 70 70 Chevrolet 50 50 a. [ 4 points] Find a ratio estimator of the 2010 total income and place a bound on the error of estimation. Interpret the results. b. [ 5 points] Find a regression estimator of the 2010 total income and place a bound on the error of estimation. Interpret the results. c. [ 3 points] Find a difference estimator of the 2010 total income and place a bound on the error of estimation. d. [ 2 points] Which of the three methods, parts (a), (b), or (c), is most appropriate in this case? Why?