When difference between compound and simple interest for three years is Rs. 152 at 4% interest per annum, the principal is Rs. ______

Correct option is C

Given:
Time = 3 years
Rate = 4% p.a.
CI − SI = Rs. 152
Formula Used:
For 3 years,
​$$\text{Difference between CI and SI} = \frac{P \times r^2 \times (300 + r)}{100^3}$$​​
Solution:
Here r = 4.
​$$CI - SI = \frac{P \times 4^2 \times (300 + 4)}{100^3} \\\ \\152 = \frac{P \times 16 \times 304}{1000000} \\\ \\152 = \frac{P \times 4864}{1000000} \\\ \\P = \frac{152 \times 1000000}{4864} \\\ \\= \frac{152000000}{4864} \\\ \\= 31250 \\\ \\\text{So, principal} = \text{Rs. } 31,250.$$​​