A sum of money becomes 27 times of itself in 18 years at compound interest. How much times will it become in 30 years?
Answer & explanation
Correct answer: option 1
ATQ,
P = 1 → 18yr → 27 or 33 (Amount)
↓ ↓
×1/3 cube-root*
↓ ↓
P = 1 → 6yr → (3)1 = 3
↓ ↓
×5 power 5*
↓ ↓
P = 1 → 30yr → (3)5 = 243
⇒ So, in 30 years it becomes 243 times
OR
Amount = P (1+ \(\frac{r}{100}\))t
ATQ,
⇒ 27P = P (1+ \(\frac{r}{100}\))18
⇒ 27 = (1+ \(\frac{r}{100}\))18
⇒ (3)3 = (1+ \(\frac{r}{100}\))18
⇒ 3 = (1+ \(\frac{r}{100}\))6
⇒ (3)5 = (1+ \(\frac{r}{100}\))30
⇒ 243 = (1+ \(\frac{r}{100}\))30
⇒ So, in 30 years it becomes 243 times.