A. 42
B. 20
C. 70
D. 54
Correct Answer: Option B
B. 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
A. 42
B. 20
C. 70
D. 54
Correct Answer: Option B
B. 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
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