Multiple choice

Joseph receives simple interest equal to the sum invested by him 4 years ago. If George wants to receive the interest equal to twice the interest received by Joseph by investing the same amount as Joseph did at half the rate of interest, he should invest the amount for

  1. 4 years

  2. 8 years

  3. 12 years

  4. 16 years

  5. None of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Joseph: SI = P, T = 4, R = r. P = (P*r*4)/100 => r = 25. George: SI = 2P, R = r/2 = 12.5, T = ?. 2P = (P*12.5*T)/100 => 2 = 0.125T => T = 16.

AI explanation

Let Joseph's principal be P, rate be R, and time be 4 years; since the simple interest equals the principal, P = P*R*4/100, which simplifies to R = 25%. George invests the same amount P at half the rate, so his rate is 12.5%, and he wants to earn twice the interest, which is 2P. Using the simple interest formula, 2P = P*12.5*T/100, so T = (200)/(12.5) = 16. He should invest the amount for 16 years.

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