More Examples of Simple Interest

To Find Principal
When interest, time, rate are given:

Example 01:
What amount was borrowed, for which amount of interest is 200 at the rate of 5% for 4 years.
Solution:
Let P = Principal , Rate = 5%, Interest = 200, time = n = 4, I = Interest
We know that

I = {\text{P}}\left(  {\text{r}} \right)\left( n \right)


{\text{P}}  = \frac{1}{{{\text{r}}n}}\,\,\,\, = \frac{{200 \times 100}}{{5 \times  4}}\,\,\,\, = 1000

To Find Principal
When amount, rate, time are given:

Example 02:
If the amount for 2 years at 6% is 4,000, what was the principal?
Solution:
Let P = Principal, Rate = 6%, n = 2, A = 4,000
We know that

\begin{gathered} {\text{A}} = {\text{P}} + \Pr n \\ {\text{A}} = {\text{P}}\left( {1 + rn} \right) \\ \Rightarrow {\text{P}} = \frac{{\text{A}}}{{1 + {\text{r}}n}}\,\,\,\,\,  = \frac{{4,000}}{{1 + \left( {6\% } \right)\left( 2 \right)}} \\ \Rightarrow P = \frac{{4,000}}{{1 + \left( {\frac{6}{{100}}} \right)  \times 2}}\,\,\,\,\, = \frac{{4,000}}{{1 + \left( {.06} \right) \times  2}}\,\,\,\,\, = \frac{{4,000}}{{1.12}}\,\,\,\,\, = 3500 \\ \end{gathered}

To Find Rate
When interest, time, principal are given:
Example 03:
The amount of simple interest for Rs.15,000 for 2 years is 1000, find rate of interest.
Solution:
Let Principal = 15,000, Simple interest = I = 1000, Time = 2 years
Interest = P r n

  \Rightarrow {\text{r}} = \frac{1}{{{\text{P}}n}}\,\,\,\,\, =  \frac{{1,000}}{{15,000 \times 2}} = \frac{{500}}{{150 \times 100}}\,\,\,\,\, =  \frac{{3.33}}{{100}}\,\,\,\,\, = 3.33\%

Comments

comments

Posted in: