2016 · Q25
If a sum of money at a certain rate of simple interest per year doubles in 5 years and at a different rate of simple interest per year becomes three times in 12 years, then the difference in the two rates of simple interest per year is
Elementary MathematicsSimple and Compound Interest
- A2%
- B3%
- C3 1/3%
- D4 1/3%
Explanation
Doubling in 5 years under simple interest: P·r₁·5 = P, so r₁ = 20%. Tripling in 12 years: P·r₂·12 = 2P, so r₂ = 50/3%. The difference is 20 − 50/3 = 10/3 = 3⅓%, option C.