Refer to the following mentioned data. Net sales Cost of products sold Gross margin (In millions) 2017 2016 2015 $34,392 $30,007 $26,504 14,112 13,072 13,425 $20,280 $16,935 $13,079 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 $12.91 billion. Calculate an estimated cost of goods sold and gross profit for the four months, using the gross profit ratio 2017. (Round intermediate calculations to 2 decimal places. Enter your answers in millions rounded to nearest whole number (.e., 5,000,000 should be entered as 5).) million Cost of goods sold Gross profit million