Ex.8.3 Q11 Compairing Quantities - NCERT Maths Class 7

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Question

If Meena gives an interest of \(\rm Rs\, 45\) for one year at \(9\%\) rate p.a.. What is the sum she has borrowed?

 Video Solution
Comparing Quantities
Ex 8.3 | Question 11

Text Solution

What is Known?

If Meena gives an interest of \(\rm Rs\, 45\) for one year at \(9\%\) rate p.a.

What is Unknown?

What is the sum she has borrowed?

Reasoning:

This question can be solved by using the formula of simple interest

 So Simple Interest 

\[\begin{align}{\rm{ = }}\frac{{{\rm{Principal}} \times {\rm{Rate}} \times {\rm{Time}}}}{{{\rm{100}}}}\end{align}\]

Steps:

Let us assume principal to be \(P\)

 So Simple Interest 

\[\begin{align}{\rm{ = }}\frac{{{\rm{Principal}}{\rm{ \times }}{\rm{Rate}}{\rm{ \times }}{\rm{Time}}}}{{{\rm{100}}}}\end{align}\]

\[\begin{align}{\rm{I}}{\rm{.E}}{\rm{.}}{\rm{45}}&= \frac{{{\rm{P}} \times {\rm{9}} \times {\rm{1}}}}{{{\rm{100}}}}\\{\rm{P}} &=\frac{{{\rm{45}}{\rm{ \times }}{\rm{1}}{\rm{00}}}}{{{\rm{9}}{\rm{ \times }}{\rm{1}}}}\\&= 500\end{align}\]

So, Meena borrowed \(\rm Rs\, 500\)