A jar contains red balls and green balls in the ratio 3:1. If the jar contains only the two types of balls, which of the following cannot be the number of balls in the jar ?

Correct Answer: 54
here, sum of ratio = 3 + 1 = 4 96/4 = 24 (divisible) 80/4 = 20 (divisible) 72/4 = 18 (divisible) 54/4 # (it is not divisible by round figure) so, ans is 54