IMO Practice Test — Compound Interest
6 Questions • 15 min • Olympiad level
15:00
Question 1 of 6
hard
The difference between CI and SI for 2 years on ₹4000 at 5% p.a. is:
₹5
₹10
₹15
₹20
Explanation: SI=400, CI=410, difference=10
Question 2 of 6
hard
A sum of money doubles itself in 5 years at CI. In how many years will it become 8 times?
10 years
12 years
15 years
20 years
Explanation: Doubles in 5 years; 8=2³, so 3×5=15 years
Question 3 of 6
hard
The compound interest on ₹15000 for 1.5 years at 8% p.a. compounded half-yearly is:
₹1836
₹1872
₹1908
₹1944
Explanation: Half-years=3, rate=4%, A=15000(1.04)³=16872, CI=1872
Question 4 of 6
hard
A machine depreciates at 10% p.a. Its present value is ₹72900. What was its value 2 years ago?
₹81000
₹90000
₹100000
₹110000
Explanation: Let past value=x; x(0.9)²=72900 → x×0.81=72900 → x=90000
Question 5 of 6
hard
The effective annual rate of interest equivalent to 8% p.a. compounded half-yearly is:
8.00%
8.16%
8.24%
8.32%
Explanation: Effective rate = (1.04)² - 1 = 1.0816 - 1 = 0.0816 = 8.16%
Question 6 of 6
hard
A sum of ₹10000 is invested at 10% p.a. CI. If interest is compounded quarterly, the amount after 6 months is:
₹10500
₹10506.25
₹10512.50
₹10525
Explanation: Quarterly rate=2.5%, periods=2, A=10000(1.025)²=10000×1.050625=10506.25