Question

A man divided Rs. 82800 in two parts, lent the first part at 12% for 7 years at simple interest, and the second part at 8% for 4 years at simple interest. If the interest earned on two parts is in the ratio of 3 : 4, find the first part?
1. 21000
2. 20000
3. 20500
4. 18400
5. 19500

Answer 1

Correct Answer - Option 4 : 18400

Given:

Total amount invested = Rs. 82800

Rate of interest for 1^st part (R₁) = 12%

Invested Time for 1^st part (T₁) = 7 years

Rate of interest for 2^nd part (R₂) = 8%

Invested Time for 2^st part (T₂) = 4 years

The ratio of S.I of 1st part (S.I₁) and S.I of 2nd part (S.I₂) = 3 : 4

Concept Used:

S.I = PRT/100

R = Rate of Interest

T = Time

Calculation:

Let the 1^st part be x and the 2^nd part is y.

S.I₁ : S.I₂ = 3 : 4

⇒ (12x)(7/100) : (8y)(4/100) = 3 : 4

⇒ x : y = 2 : 7

The total amount invested = x + y

⇒ x + y = (2 + 7) ≡ 82800

⇒ 1 ≡ 9200

⇒ x = 2 ≡ 9200 × 2

⇒ x = 18400

∴ The amount invested in 1^st part is Rs. 18400.