Select the correct answerA sum of money in 3 years becomes 1344 and in 7 years, becomes Rs. 1536. What is the principal sum where simple rate of interest is to be unchanged?Options1200150040002800

The problem is about simple interest. The formula for simple interest is I = PRT/100, where I is the interest, P is the principal amount, R is the rate of interest, and T is the time in years.

Given that a sum of money becomes Rs. 1344 in 3 years and Rs. 1536 in 7 years, we can infer that the interest accrued in the 4-year period between the 3rd and 7th years is Rs. 1536 - Rs. 1344 = Rs. 192.

We can use this information to find the rate of interest. Let's denote the principal sum as P and the rate of interest as R. Then, according to the formula for simple interest, we have:

192 = P * R * 4 / 100.

We also know that the sum of the principal amount and the interest accrued in 3 years is Rs. 1344. Therefore, we have:

P + P * R * 3 / 100 = 1344.

We can solve these two equations to find the values of P and R. However, since we are only interested in the principal sum, we can substitute the expression for R from the first equation into the second equation to find P. Doing so, we get:

P + P * 192 / (P * 4) * 3 = 1344, P + 144 = 1344, P = 1344 - 144 = 1200.

Therefore, the principal sum is Rs. 1200.