Question

In a school , there are 20 teachers who teach

Mathematics or Physics . Of these , 12 teach

Mathematics , 12 teach Physics. How many teach

both the subjects ?​

Answer 1

Answer:

n(A) = mathematics = 12

n(B)= physics = 12

n(AUB) = 20

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

20 = 12+ 12 - n ( AnB)

n(AnB) = 24-20

n(AnB) = 4 ans