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: Option B
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
There is an explanation video available below.