Question

The number of students who take both the subjects mathematics and chemistry is 30. This represents 10% of the enrolment in mathematics and 12% of the enrolment in chemistry. How many students take at least one of these two subjects ?

• A. 520
• B. 490
• C. 560
• D. 480

Answer 1

Answer: (A)

520

Answer 2

Let $x$ be the number of students who take mathematics and $y$ be the number of students who take chemistry. $30=\frac{10}{100}\left(x+30\right)$ $\Rightarrow x=270$ Similarly, $30 = \frac{12}{100}\left(y+30\right)$ $\Rightarrow y= 220$ Number of students who take atleast one of these two subjects $= 270 + 220 + 30 = 520$