Question

Re
David invested some money at the rate of 12% p.a. simple interest for 1 year. Out of the total money received
after 1 year, he donated 3 11.520 which is 200% of the interest received on the invested amount. He invested
the remaining amount for 2 years at the rate of 25% compound interest (compounded annually). Find the total
amount which lie will get after 2 years.​

Answer 1

Step-by-step explanation:

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Suppose the person invested Rs x at the rate of 12% simple interest and Rs y at the rate of 10% simple interest. Then,

Yearly interest =10012x+10010y

∴10012x+10010y=130

⇒12x+10y=13000

⇒6x+5y=6500 .(i)

In the invested amounts are interchanged, then yearly interest increased by Rs 4.

∴10010x+10012y=134

⇒10x+12y=13400

⇒5x+6y=6700 ..(ii)

Subtracting equation (ii) from equation (i), we get

x−y=−200 .(iii)

Adding equation (ii) and (i), we get

11x+11y=13200

⇒x+y=1200 ..(iv)

Adding equations (iii) and (iv), we get

2x=1000⇒x=500

Putting x=500 in equation (iii), we get y=700

Thus, the person invested Rs 500 at the rate of 12% per year and Rs 700 at the rate of 10% per year.