SETS 4

If n(A)= 60 , n(AuB) = 140 and n(AnB)=40, find n(B)

Solution

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

  140     = 60 + n(B)  – 40

  140     = 60 -40 + n(B) 

  140     = 20 + n(B) 

  140 - 20        = n(B)

  120        = n(B)

Hence n(B) = 120 answer

TRY THIS…………………………….

If n(A)= 64 , n(AuB) = 136 and n(AnB) = 31, find n(B).