For four years, Mary Nations invested $4,500 each year in America Bank stock. The stock was selling for $39 in 2010, for $52 in 2011, $38 in 2012, and for $60 in 2013. (a)What is Mary's total investment in America Bank? Total investment $ (b)After four years, how many shares does Mary own? (Round your intermediate calculations and final answer to 1 decimal place.) Total shares (c)What is the average cost per share of Mary's investment? (Round your intermediate calculations and final answer to 1 decimal place.) Average cost per share