Mathematics/General Ability MCQs
Topic Notes: Mathematics/General Ability
MCQs and preparation resources for competitive exams, covering important concepts, past papers, and detailed explanations.
Plato
- Biography: Ancient Greek philosopher (427–347 BCE), student of Socrates and teacher of Aristotle, founder of the Academy in Athens.
- Important Ideas:
- Theory of Forms
- Philosopher-King
- Ideal State
201
A certain sum of money amounts to Rs. 1008 in 2 years and to Rs. 1164 in 3.5 years at simple interest. Find the principal.
Answer:
Rs. 800
Interest for 1.5 years = 1164 - 1008 = Rs. 156. Interest for 1 year = 156 / 1.5 = Rs. 104. Interest for 2 years = 104 × 2 = Rs. 208. Principal = Amount in 2 years - Interest for 2 years = 1008 - 208 = Rs. 800.
202
At what rate percent per annum simple interest will a sum of money triple itself in 16 years?
Answer:
12.5%
If a sum P triples, Amount = 3P. SI = 3P - P = 2P. Rate R = (SI × 100) / (P × T) = (2P × 100) / (P × 16) = 200 / 16 = 12.5%.
203
Find the difference between CI and SI on Rs. 8000 for 3 years at 5% p.a.
Answer:
Rs. 61
The formula for the difference between CI and SI for 3 years is D = P(R/100)²(3 + R/100). D = 8000(5/100)²(3 + 5/100) = 8000(1/400)(3.05) = 20 × 3.05 = Rs. 61.
204
The present worth of Rs. 169 due in 2 years at 4% per annum compound interest is:
Answer:
Rs. 156.25
Present Worth (Principal) P = A / (1 + R/100)^T. Here, A = 169, R = 4, T = 2. P = 169 / (1 + 4/100)² = 169 / (1.04)² = 169 / 1.0816 = Rs. 156.25.
205
In what time will Rs. 8000 amount to Rs. 9261 at 5% per annum, compounded annually?
Answer:
3 years
Using A = P(1 + R/100)^T: 9261 = 8000(1 + 5/100)^T. This gives 9261 / 8000 = (21/20)^T. Since 9261 is 21³ and 8000 is 20³, we have (21/20)³ = (21/20)^T, so T = 3 years.
206
A sum invested at compound interest doubles itself in 4 years. In how many years will it amount to 16 times itself?
Answer:
16 years
If a sum becomes 'x' times in 'T' years at CI, it becomes x^n times in 'n × T' years. Here, it becomes 2 times in 4 years. We want 16 times, which is 2⁴. So, n = 4. Time = 4 × 4 = 16 years.
207
What is the compound interest on Rs. 2500 for 2 years at 4% per annum, compounded annually?
Answer:
Rs. 204
Amount A = 2500(1 + 4/100)² = 2500(1.04)² = 2500 × 1.0816 = Rs. 2704. CI = Amount - Principal = 2704 - 2500 = Rs. 204.
208
A sum of money amounts to Rs. 6690 after 3 years and to Rs. 10035 after 6 years on compound interest. Find the sum.
Answer:
Rs. 4460
Let the sum be P. A3 = P(1+R/100)³ = 6690. A6 = P(1+R/100)⁶ = 10035. Dividing A6 by A3 gives (1+R/100)³ = 10035 / 6690 = 1.5. Substituting this back into the first equation gives P(1.5) = 6690, so P = 6690 / 1.5 = Rs. 4460.
209
The difference between the compound interest and simple interest on a certain sum at 10% per annum for 2 years is Rs. 631. Find the sum.
Answer:
Rs. 63100
For 2 years, Difference D = P(R/100)². Substituting the values: 631 = P(10/100)² = P(1/100). Therefore, P = 631 × 100 = Rs. 63100.
210
If the compound interest on a sum of money for 3 years at 5% is Rs. 252.20, the simple interest on the same sum at the same rate and for the same time is:
Answer:
Rs. 240
Effective CI rate for 3 years at 5% = 15.7625%. Effective SI rate = 15%. Principal = 252.20 / 0.157625 = Rs. 1600. SI = 15% of 1600 = Rs. 240.