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
121
What will be the compound interest on Rs. 15625 for 9 months at 16% per annum compounded quarterly?
Answer:
Rs. 1951
Quarterly rate R = 16/4 = 4%. Time n = 9 months = 3 quarters. Amount A = 15625(1 + 4/100)³ = 15625(26/25)³ = 15625 × (17576 / 15625) = Rs. 17576. CI = 17576 - 15625 = Rs. 1951.
122
If the CI on a certain sum for 2 years at 10% is Rs. 1050, find the principal.
Answer:
Rs. 5000
Effective CI rate for 2 years at 10% is 21%. 21% of Principal = Rs. 1050. Principal = (1050 / 21) × 100 = Rs. 5000.
123
At what rate percent compound interest will Rs. 400 amount to Rs. 441 in 2 years?
Answer:
5%
Amount A = P(1 + R/100)^T. 441 = 400(1 + R/100)². (1 + R/100)² = 441 / 400. Taking the square root gives 1 + R/100 = 21 / 20 = 1.05. R/100 = 0.05, meaning R = 5%.
124
A sum of money amounts to Rs. 4840 in 2 years and to Rs. 5324 in 3 years at compound interest. What is the rate of interest?
Answer:
10%
The interest for the 3rd year is earned on the amount at the end of the 2nd year. Interest = 5324 - 4840 = Rs. 484. Rate = (484 / 4840) × 100 = 10%.
125
Find the difference between the compound interest and simple interest for 3 years on Rs. 10000 at 5% per annum.
Answer:
Rs. 76.25
Difference for 3 years = P(R/100)²(3 + R/100) = 10000(5/100)²(3.05) = 10000(1/400)(3.05) = 25 × 3.05 = Rs. 76.25.
126
What is the present worth of Rs. 1323 due in 3 years at 5% compound interest?
Answer:
Rs. 1143
Present Worth = A / (1 + R/100)^T = 1323 / (1.05)³ = 1323 / (21/20)³ = 1323 / (9261/8000) = (1323 × 8000) / 9261 = 8000 / 7 = Rs. 1142.8. Let me check the math. 21^3 = 9261. 1323 × 7 = 9261. So 1323 / 9261 = 1/7. Present worth = 8000 / 7. Let me modify the Amount to 9261 so present worth is 8000, or modify the amount to 1389.15 for 1200. Actually, if Present Worth = 1200, Amount = 1200 × 9261/8000 = 1389.15. If Amount = 1323, Present worth is not an integer. I will update the correct option to closely match standard problems where the sum is Rs 1200, but I will provide the nearest calculation.
127
A sum of money placed at compound interest becomes 3 times in 4 years. In how many years will it become 27 times?
Answer:
12 years
In compound interest, if a sum becomes x times in T years, it becomes x^n times in nT years. Here, it becomes 3 times in 4 years. To become 27 times (3³), it will take 3 × 4 = 12 years.
128
The difference between CI and SI on a sum of Rs. 5000 for 2 years is Rs. 72. Find the rate of interest.
Answer:
12%
Difference D = P(R/100)². 72 = 5000(R²/10000). 72 = R² / 2 => R² = 144. Therefore, R = 12%.
129
If the compound interest on a certain sum for 2 years at 4% is Rs. 102, the simple interest at the same rate for the same time will be:
Answer:
Rs. 100
Effective CI rate = 4 + 4 + 16/100 = 8.16%. Effective SI rate = 8%. Since 8.16% of P = 102, P = (102 / 8.16) × 100 = 1250. SI = 8% of 1250 = Rs. 100.
130
Find the compound interest on Rs. 10000 for 1.5 years at 10% per annum, compounded half-yearly.
Answer:
Rs. 1576.25
Rate per half year = 5%. Time = 1.5 years = 3 half-years. Amount = 10000(1.05)³ = 10000 × 1.157625 = Rs. 11576.25. CI = 11576.25 - 10000 = Rs. 1576.25.