Refer to the following mentioned data. Required: a. Calculate the gross profit ratio for each of the past three years. (Round your answers to 2 decimal places.) b. Assume that Campbell's net sales for the first four months of 2018 totaled $12.11 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. Enter your answers in millions rounded to nearest whole number (i.e., 5,000,000 should be entered as 5).)