Answer 19:1
Work:
Students scoring above 80 -
9+18+72+15= 114
Students score exactly 80-
6
114/6 = 19
19 students scored above 80 for every 1 student that scored exactly 80.
NormalCdf(-2,2,0,1)=.9545
95.45%
<span>$125 is to be paid during the 6th month.</span>
Question not clear, i think it's incomplete else sorry