Question

the compound interest on a sum of money for 2 years is rupees 410 and the simple interest on the same sum for the same period and at the same rate is rupees 400 find the sum and the rate of interest.
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Answer 1

Given that SI in 2 years = Rs 400

⇒ SI for 1 year = Rs 400/2 = Rs 200 Hence CI for 1 year = Rs 200 Given compound interest for 2 years = Rs 410 Therefore CI for 2 years = CI for 1st year + CI for 2nd year

⇒ CI for 2nd year = Rs 410 – Rs 200 = Rs 210 That is interest on Rs 200 for 1 year = Rs 210 – Rs 200 = Rs 10

⇒ 2R = 10 ∴ R = 5%