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)

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
$=270+220+30=520$