Multiple choice

Yoshua wanted to make an investment in the banking sector, so he invested a certain sum of money at d% interest per annum for 30 years. At the end of the period, he would get thrice the amount he invested. At what percentage of interest did he invest the money?

  1. 3.98%

  2. 4.33%

  3. 5.58%

  4. 6.67%

  5. 7.12%
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Simple interest I = P * r * t / 100. Here, the final amount is 3P, so interest I = 2P. 2P = P * r * 30 / 100. 2 = 0.3r. r = 2 / 0.3 = 6.666...% which rounds to 6.67%.

AI explanation

Since the amount becomes thrice the principal, the total simple interest earned is 2P. Using the simple interest formula SI = (P * R * T) / 100, we substitute the known values to get 2P = (P * d * 30) / 100. Dividing both sides by P gives 2 = 30d / 100. Solving for d yields d = 200 / 30, which is 6.67%.

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