Question

What will be the rate of simple interest so that ₹750 amounts to ₹1200 in 6 years ​

Answer 1

Answer :-

• The rate of interest is 10% per annum.

To find :-

• The rate of interest.

Solution :-

• Before finding the rate of interest, let's find the simple interest.

We know that :-

$\underline{ \boxed{\sf SI = Amount -Principal }}$

Where,

• SI = Simple Interest.

Here,

• Amount = Rs 1200.
• Simple interest = Rs 750.

Therefore,

$\boxed{\hookrightarrow \bf SI = 1200 - 750}$

$\boxed{\bf\hookrightarrow SI = Rs \: 450.}$

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• Now, as we know the simple interest, let's find the rate of interest!

We know that :-

$\underline{ \boxed{ \sf SI = \dfrac{Principal \times Rate \times Time}{100}}}$

Where,

• SI = Simple Interest.

Here,

• Simple interest = Rs 450.
• Principal = Rs 750.
• Time = 6 years.

Let :-

• The rate of interest be "r" %.

Substituting the given values in this formula,

$:\longmapsto\tt450 = \dfrac{750 \times r \times 6}{100}$

$\tt: \longmapsto 450 = \dfrac{4500 \times r}{100}$

$\tt: \longmapsto 450 = \dfrac{4500r}{100}$

$\tt: \longmapsto 450 \times 100 = 4500r$

$\tt: \longmapsto 45000 = 4500r$

$\tt: \longmapsto \dfrac{45000}{4500} = r$

$:\longmapsto{\overline{\boxed{ \tt 10\% = r}}}$

________________________________

Hence :-

• The rate of interest will be 10% per annum so that Rs 750 amounts to Rs 1200 in 6 years.

Answer 2

$\underline{\underline{\huge{\pink{\tt{\textbf Answer :-}}}}}$

Let the rate of the interest be R and,

the amount on Rs. 1200 be A.

Simple interest is given by the formula

$i = \frac{p \times r \times t}{100}$

where,P is the Principal amount

R is the rate of interest

T is the time

i is the simple interest

For Simple interest value, subtract the principal from the amount

i=885-750

i=135

Here

P=750

i=135

T=3

By substituting these values in above formula

$135 = \frac{750 \times r \times 3}{100}$

750×r×3=135×100

2250r=13500

r=6%