The simple interest on a sum of money will be Tk. 600 after 10 years. If the principal is trebled after 5 years, what will the total interest at the end of the tenth year ?

A Tk. 600

B Tk. 1,200

C Tk. 900

D Tk. 1,500

Correct Answer: Option B

Solution:

10 বছর পর কোনো আসলের সরল সুদ 600 টাকা হবে । 5 বছর পর আসল 3 গুণ হলে 10 বছর পর মোট সুদ কত হবে ?

Amount of interest in 10 years = 600 Tk.

Amount of interest in 1 years = \(\frac{{600}}{{10}} = 60\) Tk.

In simple interest, when the Principal is trebled, the interest will also be trebled.

Amount of interest in the first 5 years = 5 \( \times \) 60 = 300 Tk.

And the amount of interest in the next 5 years = 60 \( \times \) 5 \( \times \) 3 = 900 Tk.

At the end of tenth year total interest will be = 300 + 900 = 1,200 Tk.