A sum of money becomes ₹ 13380 after 3 years and ₹ 20070 after 6 years on compound interest. Find the sum. (L.I.C.A.A.O., 2007)
Answer
Answer (as printed):
Explanation
Let the sum be ₹ P. Then, $$P\left(1+\frac{R}{100}\right)^{3}=13380$$ and $P\left(1+\frac{R}{100}\right)^{6}=20070$ On dividing, we get: $\left(1+\frac{R}{100}\right)^{3}=\frac{20070}{13380}=\frac{3}{2}$. Substituting this value in (i), we get; $$P \times \frac{3}{2}=13380 \quad \text { or } \quad P=\left(13380 \times \frac{2}{3}\right)=8920 .$$ Hence, required sum $=₹ 8920$.
Explanation as extracted from the printed page; notation may be imperfect.