Question

What rate gives Rs 280 as interest on a sum of Rs 56,000 in 2 years?

Answer 1

Hint- Here, we will be using the formula for simple interest.
Given, Sum or Principle value $P = {\text{ Rs 56000}}$
Time $T = 2{\text{ years}}$
Simple Interest $SI = {\text{ Rs 280}}$
Let the rate of simple interest be $R$ percent.
 As we know that the simple interest is given by
$SI = \dfrac{{P \times R \times T}}{{100}} \Rightarrow 280 = \dfrac{{56000 \times R \times 2}}{{100}} \Rightarrow R = \dfrac{{280 \times 100}}{{56000 \times 2}} = 0.25$ percent.
Hence, the rate of the simple interest that gives Rs 280 as interest on a sum of Rs 56,000 in 2 years is 0.25 percent per year.

Note- In these types of problems, a simple interest formula is used where the value of all the parameters are known except for one (in this case the unknown parameter is rate percent of simple interest) which can be easily determined using algebra.