Question

A sum of money invested at simple interest amounts to 2480 at the end of four years and 4080 at the end of eight years. Find the principal.

• A. 2040
• B. 1480
• C. 1240
• D. 880

Answer 1

The correct option is D 880

Simple Interest $SI=\frac{PNR}{100}$
Also Amount $A=P+SI$
So, for four years,
$2480-P=\frac{P\times 4\times R}{100}$ -- (1)
And, for eight years,
$4080-P=\frac{P\times 8\times R}{100}$ -- (2)
Subtracting equation (1) from equation (2), we get
$=>1600=\frac{4PR}{100}$
$=>PR=40,000$
Substituting it in equation (1), we get
$2480-P=\frac{4\times 40,000}{100}$
$=>P=Rs$ $880$