A 4-column table with 3 rows. The first column has no label with entries before 10 p m, after 10 p m, total. The second column is labeled 16 years old with entries 0. 9, a, 1. 0. The third column is labeled 17 years old with entries b, 0. 15, 1. 0. The fourth column is labeled total with entries 0. 88, 0. 12, 1. 0 Determine the values of the letters to complete the conditional relative frequency table by column. A = b =.