Mr. Rony invested an amount of Tk. 1800 divided in two different schemes X and Y at the simple interest rate of 12% p.a. and 10% p.a. respectively. If the total amount of simple interest earned in 3 years be Tk. 558, what was the amount invested in Scheme Y?

Question: Mr. Rony invested an amount of Tk. 1800 divided in two different schemes X and Y at the simple interest rate of 12% p.a. and 10% p.a. respectively. If the total amount of simple interest earned in 3 years be Tk. 558, what was the amount invested in Scheme Y?

Solution:
Let,
The amount invested in Scheme X = Tk. a
Then, the amount invested in Scheme Y = Tk. (1800 - a)

So the interest of X schemes =Tk. {a × (12/100) × 3}
= 9a/25
So the interest of Y schemes =Tk. {(1800- a) × (10/100) × 3}
= 540 - (3a/10)

ATQ,
(9a/25) + 540 - (3a/10) = 558
⇒ 9a/25 - 3a/10 = 558 - 540
⇒ (18a - 15a)/50 = 18
⇒ 3a/50 = 18
⇒ 3a = 18 × 50
⇒ 3a = 900
∴ a = 300

Amount in Scheme Y = Tk. (1800 - 300)
= Tk. 1500