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
411
A grocer sells 5 items for an average of Rs. 40. If the first four items cost Rs. 30, Rs. 35, Rs. 45, and Rs. 50, what is the cost of the 5th item?
Answer:
Rs. 40
Total target cost for 5 items = 5 * 40 = 200. Cost of the first four items = 30 + 35 + 45 + 50 = 160. Cost of the 5th item = 200 - 160 = Rs. 40.
412
The average age of 11 cricket players is 20 years. If the age of the coach is also included, the average age increases by 10%. The age of the coach is:
Answer:
44 years
Current average = 20 years. Total age of 11 players = 11 * 20 = 220 years. A 10% increase in average means the new average is 20 + 2 = 22 years. With the coach, there are 12 people. Total age = 12 * 22 = 264 years. Coach's age = 264 - 220 = 44 years.
413
The average salary of 20 male employees is Rs. 15,000 and that of 30 female employees is Rs. 10,000. What is the average salary of all employees?
Answer:
Rs. 12,000
Total salary of males = 20 * 15,000 = 300,000. Total salary of females = 30 * 10,000 = 300,000. Total salary of all 50 employees = 300,000 + 300,000 = 600,000. Average salary = 600,000 / 50 = Rs. 12,000.
414
In a family of 5 members, the average age at present is 33 years. The youngest member is 9 years old. The average age of the family just before the birth of the youngest member was:
Answer:
30 years
Present total age of 5 members = 5 * 33 = 165 years. 9 years ago (just before the youngest was born), the total age of the remaining 4 members was 165 - (5 * 9) = 165 - 45 = 120 years. Their average age then = 120 / 4 = 30 years.
415
The average of 5 quantities is 6. The average of 3 of them is 8. What is the average of the remaining two numbers?
Answer:
3
Total sum of 5 quantities = 5 * 6 = 30. Sum of 3 quantities = 3 * 8 = 24. Sum of the remaining 2 = 30 - 24 = 6. Average of remaining two = 6 / 2 = 3.
416
Average of 10 numbers is 7. What will be the new average if each of the numbers is multiplied by 8?
Answer:
56
If each number in a set is multiplied by a constant factor, the average is also multiplied by that same factor. New average = 7 * 8 = 56.
417
The average of 5 numbers is 14. If 2 is added to the first, 4 to the second, 6 to the third, 8 to the fourth, and 10 to the fifth, the new average is:
Answer:
20
Total increase in the sum = 2 + 4 + 6 + 8 + 10 = 30. The average increase is the total increase divided by the number of items: 30 / 5 = 6. The new average is 14 + 6 = 20.
418
A shopkeeper's average daily profit for the first 15 days of a month is Rs. 250, and for the next 15 days is Rs. 300. What is his average daily profit for the 30 days?
Answer:
Rs. 275
Total profit for first 15 days = 15 * 250 = 3750. Total profit for next 15 days = 15 * 300 = 4500. Total for 30 days = 3750 + 4500 = 8250. Average = 8250 / 30 = 275. Alternatively, since the number of days is equal (15 and 15), simply average the two averages: (250 + 300) / 2 = 275.
419
The average of all odd numbers up to 100 is:
Answer:
50
The odd numbers up to 100 are 1, 3, 5, ..., 99. The average of an arithmetic progression is (first term + last term) / 2 = (1 + 99) / 2 = 100 / 2 = 50.
420
The average weight of 10 oarsmen in a boat is increased by 1.8 kg when one of the crew, who weighs 53 kg is replaced by a new man. The weight of the new man is:
Answer:
71 kg
Total weight increase = 10 * 1.8 = 18 kg. This increase is because the new man is heavier. Weight of the new man = weight of replaced man + increase = 53 + 18 = 71 kg.