Question

A person invested in all Rs 2600 at 4%, 6% and 8% per annum simple interest. At the end of the year, he got the same interest in all the three cases. The money invested at 4% is : 

(a) Rs 200 

(b) Rs 600 

(c) Rs 800 

(d) Rs 1200

Answer 1

(d) Rs 1200.

Let the three parts be x, y and z. Then,

\(\frac{x\times4\times1}{100}\) = \(\frac{y\times6\times1}{100}\)= \(\frac{z\times8\times1}{100}\)

⇒ 0.04 x = 0.06 y = 0.08 z

⇒ \(\frac{x}{y} = \frac{0.06}{0.04} = \frac{3}{2}\) and \(\frac{y}{z} = \frac{0.08}{0.06} = \frac{8}{6} = \frac{4}{3}\)

⇒ \(\frac{x}{y} = \frac{6}{4}\) and \(\frac{y}{z} = \frac{4}{3}\) ⇒ x : y : z = 6 : 4 : 3

∴ Sum invested at 4 % = \(\frac{6}{13}\) x Rs 2600 = Rs 1200.