Given:
Compound interest for the 3rd year = Rs.
Rate of interest = 10%
Concept used:
Tree method
Calculation:
Let the principal be Rs. x
So, for 2nd and 3rd year principal be 2x and 3x
According to the question,
x/10
2x/10 x/100
3x/10 3x/100 x/1000
(3x/10 + 3x/100 + x/1000) = 1158.50
⇒ (300x + 30x + x)/1000 = 1158.50
⇒ 331x = 1158500
⇒ x = 3500
⇒ The principal = Rs. 3500
∴ The sum he has deposited each year is Rs. 3500