1.

1/3rd of a principal amount is kept at simple interest in the post office at a rate of 15% per annum, and rest is kept in the bank at compound interest at the rate of 10% per annum. Find the total amount invested if the difference between compound interest and simple interest for two years be Rs. 480.1. Rs 120002. Rs 80003. Rs 40004. Rs 16000

Answer» Correct Answer - Option 1 : Rs 12000

Given:     

SI rate of interest = 15%

CI rate of interest = 10%

Difference between compound interest and simple interest for two years = Rs. 480.

Formula Used:

Simple Interest = (P × R × T)/100    

Compound Interest = P(1 + R/100)T – P  

Where,

P → Principal 

R → Rate of interest 

T → Time 

Calculations:

Let the total principal be x

Simple Interest in two years = ((x/3) × 15 × 2)/100 = x/10

Compond Interest in two years = (2x/3)(1 + 10/100)2 – 2x/3

⇒ (2x/3) × 121/100 – 2x/3

⇒ (121x/150) – 2x/3

⇒ 21x/150

According to the querstion,

⇒ (21x/150) – (x/10) = 480

⇒ 6x/150 = 480

⇒ x = 12000

∴ The total amount invested was Rs. 12000



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