Problem 14-12 Using Dollar Cost Averaging [LO14-5] For four years, Mary Thomas invested $4.320 each year in America Bank stock. The stock was selling for $68 in 2018 , for $64 in 2019 . for $65 in 2020, and for $57 in 2021 . a. What is Mary's total investment in America Bank? b. After four years, how many shares does Mary own? Note: Round your intermediote calculations to 1 decimal place. Round up your final answer to the nearest whole unit. c. What is the average cost per share of Mary's investment? Note: Round up your intermediate value of "Total shares" to the nearest whole unit. Round your final answer to 2 decimal places