Question

Find in how much time Rs. $$300$$ will yield Rs. $$60$$ interest at $$5\% $$ per annum.

Answer 1

Hint: The given data has the following parameters, Principal, Simple Interest and Rate of Interest. We need to find the time in which the principal amount will yield the given simple interest when the rate of interest is known. We use the formula for calculating simple interest and find out the time.
The formula for simple interest is,
$$SI = \dfrac{{PTR}}{{100}}$$
Where, $$SI$$ is the Simple interest, in Rupees.
$$P$$ is the Principal amount in Rupees.
$$T$$ is time, in years
$$R$$ is the rate of interest, in percentage.

Complete answer:
We can write the given data as follows,
$$\eqalign{
  & P = 300 \cr
  & SI = 60 \cr} $$
$$\eqalign{
  & R = 5\% \cr
  & T = ? \cr} $$
We use the above formula,
$$SI = \dfrac{{PTR}}{{100}}$$
Let us substitute the given data,
$$ \Rightarrow 60 = \dfrac{{300 \times T \times 5}}{{100}}$$
Now, let us simplify the RHS,
$$ \Rightarrow 60 = 15 \times T$$
Now, let us keep T in LHS,
$$ \Rightarrow T = \dfrac{{60}}{{15}}$$

And by simplifying the fraction we get,
$$ \Rightarrow T = 4$$
Therefore, the time period will be $$4$$ years, which gives us the final answer.

Additional Information:
Simple interest is a quick and an easy method to find out the interest charge on a loan. It is determined by multiplying the principal, time and rate of interest and dividing the whole by hundred. It is calculated on the principal amount on a loan or the initial contribution in a savings account.

Note:
We are only given the parameters; it is not mentioned if it is simple interest or compound interest. So, we need to figure out which interest it would be, just by seeing it. Also, note that the principal amount will always be greater than the simple interest. The time period will usually be a whole number.