SETS 1

If n(A)= 78 , n(B)= 90 and n(AuB)= 140, find n(AnB).

Solution

n(AuB) = n(A) + n(B) - n(AnB)

140 = 78 + 90 - n(AnB)

140 = 168 - n(AnB)

140 - 168 = - n(AnB)

-28 = -n(AnB)

n(AnB) = 28 [after dividing by -1 both sides]

Hence n(AnB) = 28 answer

TRY THIS………….

If n(A)= 71 , n(B)= 88 and n(AuB)= 125, find n(AnB).