Question

the simple interest on a certain sum of money at the rate of 4% p.a. for 5 years is rs. 1680. at what rate of interest the same amount of interest can be received on the same sum after 4 years ?

Answer 1

Since 1st Interest = 2nd Interest

and 1st Principal = 2nd Principal

Therefore

P× 1st rate×1st time = P× 2nd rate × 2nd time.

On canceling P from both sides...

4% × 5 year = 2nd rare × 4 year

Hence 2nd rate interest will be 5 %.

Ans.

Answer 2

Answer:

5%

Step-by-step explanation:

Let the principal be x

rate of interest = 4%

Time = 5 years

SI = Rs.1680

$SI =\frac{P \times R \times T}{100}$

$1680 =\frac{x \times 4 \times 5}{100}$

$\frac{1680 \times 100}{ 4\times 5} =x$

$8400 =x$

Now we are supposed to find that at what rate of interest the same amount of interest can be received on the same sum after 4 years

So, Principal = 8400

Time = 4 years

SI =  Rs.1680

$SI =\frac{P \times R \times T}{100}$

$1680 =\frac{8400 \times R \times 4}{100}$

$\frac{1680 \times 100}{ 4 \times 8400} =R$

$5\% =R$

Hence at  5% rate of interest the same amount of interest can be received on the same sum after 4 years .