SETS F2

 If n(A)= 55 , n(B)= 90 and n(AuB)= 136, find n(AnB).

 

Solution

 

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

 

136 = 55 + 90 - n(AnB)

 

136 = 145 - n(AnB)

 

136 - 145 = - n(AnB) [after transferring 145 on the left hand side]

 

-9 = -n(AnB)

 

n(AnB) = 9 [after dividing by -1 both sides]

 

Hence n(AnB) = 9 answer