A person invested a total sum of Rs. 7900 in three different schemes of simple interest at 3%, 5% and 8% per annum. At the end of one year…

Let the amount in 3% be x, in 5% be y and then in 8% is (7900 - x - y)

According to the problem statement, Since the interest after 1 year is same

⇒ (x × 3 × 1 )/100 = (y × 5 × 1)/100 = {(7900 - x - y) × 8 × 1}/100

Using first two relations

⇒ 3x = 5y

⇒ y = 3x/5 ----(i)

Solving 1st and 3rd equation

⇒ 3x = 63200 – 8x – 8y Using (i)

⇒ 11x = 63200 - 8 × (3x/5)

⇒ (79x)/5 = 63200

⇒ x = 4000

∴ The money invested in 3% is Rs. 4000