Question: A sum of money lent out at compound interest increases in value by 50% in 5 yr. A person wants to lend three different sums x, y and z for 10, 15 and 20 yr, respectively at the above rate in such, a way that he gets back equal sums at the end of their respective periods. The ratio x : y : z is
Options:
A) 6: 9: 4
B) 9: 4: 6
C) 9: 6: 4
D) 6: 4: 9
Show Answer
Answer:
Correct Answer: C
Solution:
- Compound interest
$ =x{{( 1+\frac{50}{100} )}^{10}}=y{{( 1+\frac{50}{100} )}^{15}}=z{{( 1+\frac{50}{100} )}^{20}} $
According to the question,
$ {{( \frac{3}{2} )}^{2}}x={{( \frac{3}{2} )}^{3}}y={{( \frac{3}{2} )}^{4}}z=klet $
$ \Rightarrow $ $ x={{( \frac{2}{3} )}^{2}}k, $ $ y={{( \frac{2}{3} )}^{3}}k $ and $ z={{( \frac{2}{3} )}^{4}}k $
$ \therefore $ $ x:y:z={{( \frac{2}{3} )}^{2}}k:{{( \frac{2}{3} )}^{3}}k:{{( \frac{2}{3} )}^{4}}k $
$ =1:\frac{2}{3}:{{( \frac{2}{3} )}^{2}}=9:6:4 $