Refer to the following mentioned data. Net sales Cost of products sold Gross margin (In millions) 2017 2016 2015 $34,994 $30,196 $26,879 14,249 13,537 13,919 $20,745 $16,659 $12,960 Required: a. Calculate the gross profit ratio for each of the past three years. (Round your answers to 2 decimal places.) 2017 2016 2015 b. Assume that Campbell's net sales for the first four months of 2018 totaled $12.53 billion Calculate an estimated cost of goods sold and gross profit for the four months, using the gross profit ratio for 2017 (Round intermediate calculations to 2 decimal places. Entel your answers in millions rounded to nearest whole number i.e., 5,000,000 should be entered as 5 million Cost of goods sold Gross proft