Multiple choice

What sum of money will amount to $Rs.\,520$ in $5$ years and to $Rs.\,568$ in $7$ years at simple interest?

  1. (a)$\;Rs.\,400$
  2. (b)$\;Rs.\,120$
  3. (c)$\;Rs.\,510$
  4. (d)$\;Rs.\,220$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Amount in 5 years = P + 5I = 520. Amount in 7 years = P + 7I = 568. Difference: 2I = 48, so I = 24 per year. P + 5(24) = 520 => P + 120 = 520 => P = 400.

AI explanation

The difference between the amounts for 7 years and 5 years represents the interest for 2 years, so Rs. 568 minus Rs. 520 equals Rs. 48. This makes the annual interest Rs. 24, meaning the interest for 5 years is Rs. 120. The principal is the initial amount minus this interest, so Rs. 520 minus Rs. 120 equals Rs. 400.

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