SETS 2

If n(A)= 90 , n(AuB) = 140 and n(AnB)=30, find n(B)

Solution

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

  140     = 90 + n(B)  – 30

  140     = 90 -30 + n(B) 

  140     = 60 + n(B) 

  140 - 60        = n(B)

  80        = n(B)

Hence n(B) = 80 answer

TRY THIS…………………………….

If n(A)= 70 , n(AuB) = 137 and n(AnB) = 35, find n(B).