Q. What sum of money will amount to 520 Rs. in 5 years and to 568 Rs. in 7 years at simple interest?
Answer: 400 Rs
Notes: Simple interest for 2 years = (568 - 520) Rs. = 48 Rs. ∴ Interest for 5 years = $latex = \frac{48}{2}\times 5 = 120 Rs. &s=1$ Principal = (520 - 120) = 400 Rs. Hence option [B] is the right answer

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