Question

A sum of money lent on simple interest, becomes 7/5 of itself in 4 years. Find the rate of interest per annum.​

Answer 1

Answer:

10%

Step-by-step explanation:

7/5=40%

40/4=10

therefore,Answer=10%

Answer 2

✬ Rate of Interest = 10 % p.a ✬

Step-by-step explanation:

Given:

• A sum of money lent on S.I becomes 7/5 of itself.
• Time given is 4 years.

To Find:

• What is rate of interest per annum?

Solution: Let the principal p be 100.

➱ Amount = 7/5 of P

➱ Amount = 7/5 x 100

➱ Amount = 7 x 20 = 140

∴ Interest = Amount – Principal

➫ Interest = 140 – 100

➫ Interest = Rs 40

• Now, we have to find the Rate (R) •

★ S.I = Principal x Rate x Time/100 ★

$\small\implies{\sf }$ 40 = 100 x R x 4/100

$\small\implies{\sf }$ 40 x 100 = 400R

$\small\implies{\sf }$ 4000 = 400R

$\small\implies{\sf }$ 4000/400 = R

$\small\implies{\sf }$ 10 % = R

Hence, The Rate of interest per annum is 10%.