QUESTION

CSAT

Hard

Maths

Prelims 2016

In aid of charity, every student in a class contributes as many rupees as the number of students in that class. With the additional contribution of Rs. 2 by one student only, the total collection is Rs. 443. Then how many students are there in the class?

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Explanation

Let's assume the number of students in the class is $x$ .

Each student contributes $x$ rupees, so the total contribution from all students is $x \cdot x$ . One student contributes an additional 2 rupees, so the total contribution is $x \cdot x + 2$ . We are given that the total contribution is 443 rupees: $x^2 + 2 = 443$ $x^2 = 443 - 2$ $x^2 = 441$ $x = \sqrt{441}$ $x = 21$