passpadi

2019

Mathematics

JAMB

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

A.

42

B.

20

C.

70

D.

54

Correct Answer: 20

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

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
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