Answer: 0.67
Work Shown:
n(A only) = number of items inside set A only
n(A only) = 12
n(A and B) = 16
n(B only) = 20
n(A or B) = n(A only) + n(A and B) + n(B only)
n(A or B) = 12 + 16 + 20
n(A or B) = 48
n(Total) = n(A only) + n(A and B) + n(B only) + n(Not A, not B)
n(Total) = 12+16+20+24
n(Total) = 72
P(A or B) = n(A or B)/n(Total)
P(A or B) = 48/72
P(A or B) = 0.67 approximately