Page 214 - Start Up Mathematics_8 (Non CCE)

2. Sahil invested ` 40,000 in a certain policy at the compound interest of 5% per annum. After a certain
period of time, he received ` 44,100. Find the period of time for which the amount was invested. Give
one point which you think one should keep in mind while investing in policies.
3. The population of a town increases at the rate of 8% per annum. If the present population is 80,000, what
will be the population after 2 years? Why should population be controlled?
4. To complete a project of Metro Railways in 4 years, 7,500 workers were employed. At the end of the first
year 15% workers were retrenched. At the end of the second year 20% of those working at that time were
retrenched. In order to complete the project on time, the number of workers was increased by 15% at the
end of the third year. How many workers were working during the fourth year? What is the importance
of completing a project on time?

Some NCERT Textbook Questions

1. Kamala borrowed ` 26,400 from a Bank to buy a scooter at a rate of 15% p.a. compounded yearly. What
amount will she pay at the end of 2 years and 4 months to clear the loan?
(Hint: Find A for 2 years with interest is compounded yearly and then find SI on the 2nd year amount
for 4 years).
12
2. Vasudevan invested ` 60,000 at an interest rate of 12% per annum compounded half yearly. What amount
would he get
(i) after 6 months?
(ii) after 1 year?
1
3. Find the amount which Ram will get on ` 4096, if he gave it for 18 months at 12 % per annum, interest
being compounded half yearly. 2
4. The population of a place increased to 54,000 in 2003 at a rate of 5% per annum
(i) find the population in 2001.
(ii) what would be its population in 2005?
5. A scooter was bought at ` 42,000. Its value depreciated at the rate of 8% per annum. Find its value after
one year.

Exemplar Problems

1. Ashima took a loan of ` 1,00,000 at 12% per annum compounded half-yearly. She paid ` 1,12,360.
2
If (1.06) is equal to 1.1236, then the period for which she took the loan is:
1
(a) 2 years (b) 1 year (c) 6 months (d) 1 years
2

Ê 5 ˆ 3
2. If the amount on the principal of ` 6,000 is written as 6,000 1+ 100¯ ˜ and compound interest payable
Á
Ë
half-yearly, then rate of interest per annum is ____________ and time in years is ____________.
3. Compound interest is the interest calculated on the previous year’s amount. (True/False)
4. Rahim borrowed ` 10,24,000 from a bank for one year. If the bank charges interest of 5% per annum
compounded half-yearly, what amount will he have to pay after the given time period. Also, find the
interest paid by him.
5. If principal = ` 1,00,000, rate of interest = 10% compounded half-yearly. Find:
(i) interest for 6 months. (ii) amount after 6 months.
(iii) interest for next 6 months. (iv) amount after one year.

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