In a survey of 50 newspaper readers, 40 read Champion and 30 read Guardian, how many read both papers?
- 10
- 5
- 15
-
20
The correct answer is: D
Explanation
Let C n G = X
n C only = 40 - x
n G only = 30 - x
40 - X + 30 - X + X = 50
70 - X = 50
X = 70 - 50
X = 20
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