Question

In a class of 50 students, 40 students offered Physics and 30 offered Biology. How many offered both Physics and Biology?

Answer 1

20 students are in biology and in physics

Answer 2

20 students offered both physics and biology.

Explanation:

n(Total) = 50

n(Physics) = 40

n(Biology) = 30

Let n(Physics and Biology) = x

n(Physics only) = 40 -x

n(Biology only) = 30 - x

40 - x + 30 - x + x = 50

70 - x = 50

x = 20