A certain sum becomes 3-fold at 4% annual rate of interest. At what rate, will it become 6-fold? Option 1: 9% Option 2: 10% Option 3: 11% Option 4: 12%

Answer: 10%. Solution: Let the original principal amount be P. When the money becomes 3-fold at 4% annual rate: Final Amount = 3P Interest Earned = 3P - P Interest Earned = 2P Using the simple interest formula where Rate = 4% and Time = T years: Interest = (P x R x T)/100 2P = (P x 4 x T)/100 2 = 4T/100 200 = 4T T = 50 years For the money to become 6-fold in the same time period of 50 years: Final Amount = 6P Interest Earned = 6P - P Interest Earned = 5P Let the required rate be R%. 5P = (P x R x 50)/100 5 = 50R/100 500 = 50R R = 10% Therefore, the rate of interest required for the sum to become 6-fold is 10%.

Arithmetic

Simple & Compound Interest

Medium

A certain sum becomes 3-fold at 4% annual rate of interest. At what rate, will it become 6-fold?

10%

11%

12%

✅ Correct Option: 2

Let the original principal amount be $P$ .

When the money becomes 3-fold at 4% annual rate:

Final Amount $= 3P$

Interest Earned $= 3P - P$

Interest Earned $= 2P$

Using the simple interest formula where Rate $= 4\%$ and Time $= T$ years:

$\text{Interest} = \dfrac{P \times R \times T}{100}$

$2P = \dfrac{P \times 4 \times T}{100}$

$2 = \dfrac{4T}{100}$

$200 = 4T$

$T = 50$ years

For the money to become 6-fold in the same time period of 50 years:

Final Amount $= 6P$

Interest Earned $= 6P - P$

Interest Earned $= 5P$

Let the required rate be $R\%$ .

$5P = \dfrac{P \times R \times 50}{100}$

$5 = \dfrac{50R}{100}$

$500 = 50R$

$R = 10\%$

Therefore, the rate of interest required for the sum to become 6-fold is $10\%$ .

2026: 30 May Shift 2

Consider the simple interest of the following

(A) A sum of Rs 200 at 6% per annum for 5 yr.

(B) A sum of Rs 2000 at $13\frac{1}{2}$ % per annum for 4 yr.

(D) A sum of Rs 68000 at $16\frac{2}{3}$ % per annum for 9 months.

Arrange the above in descending order.

Choose the correct answer from the options given below:

2022: 8 Aug Shift 1

If P = Rs. 2000, R = 5% per annual, T = 5 year

A. Total sum of amount = Rs. 2200

B. SI = Rs. 200

C. SI = Rs. 500

D. Total sum of amount = Rs. 2500

Choose the correct answer from the potions given below:

2026: 24 May Shift 1

At what rate of compound interest per annum, a sum of Rs 1800 becomes Rs 2178 in two years?

2026: 29 May Shift 2

Find a simple interest on ₹ 7200 for 7 years at a rate of 14% per annum.

2025: 20 May Shift 1

Consider the compound interest of the following

(A) The compound interest on Rs 16000 at 20% per annum for 9 months, compounded quarterly is: Rs 2522

(B) The compound interest on Rs 2800 at 10% per annum for 18 months, compounded annually is: Rs 434

Choose the correct statement(s):

2025: 29 May Shift 2

If the interest is payable annually, then the principal amount on which the compound interest for 2 years at 5% per annum is ₹ 369, is given by

A certain sum becomes 3-fold at 4% annual rate of interest. At what rate, will it become 6-fold?

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