The compound interest on a certain sum for 2 years at 12% per annum is Tk. 795. The simple interest on the same sum for double the time at half the rate percent per annum is-

Question: The compound interest on a certain sum for 2 years at 12% per annum is Tk. 795. The simple interest on the same sum for double the time at half the rate percent per annum is-

Solution:
Let
The sum be Tk. P

ATQ,
P{1 + (12/100)}² - P = 795
⇒ P[{1 + (3/25)}² - 1] = 795
⇒ P{(28/25)² - 1} = 795
⇒ P{(784/625) - 1} = 795
⇒ P(159/625) = 795
⇒ P = (795 × 625)/159
∴ P = 3125

So The simple interest on the same sum for double the time at half the rate percent per annum is-
SI = 3125 × 4 × 6%
= 3125 × 4 × 6/100
= 750