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
311
The average of 4 numbers is 25. If a fifth number 35 is added, what will be the new average?
Answer:
27
Total of first 4 numbers = 4 × 25 = 100. Add 35 → new sum = 135. Average = 135 ÷ 5 = 27.
312
The average of numbers from 1 to 99 is:
Answer:
50
Average of consecutive numbers = (first + last) ÷ 2. For 1 to 99: (1 + 99) ÷ 2 = 50.
313
The average age of 5 students is 12 years. If a teacher aged 32 joins them, what is the new average age?
Answer:
15.33
Total age of students = 5 × 12 = 60. Adding teacher = 60 + 32 = 92. New average = 92 ÷ 6 = 15.33.
314
The average of 9 numbers is 50. If one number 70 is replaced by 40, what will be the new average?
Answer:
46.67
Total of 9 numbers = 9 × 50 = 450. Replacing 70 with 40 reduces sum by 30 → new sum = 420. New average = 420 ÷ 9 = 46.67.
315
The average of 5 consecutive numbers is 18. What is the smallest number?
Answer:
16
In consecutive numbers, the average equals the middle number. So the numbers are 16, 17, 18, 19, 20. Smallest number = 16.
316
The average of 7 numbers is 14. If one number is 28, what is the average of the remaining six numbers?
Answer:
11.67
Total of 7 numbers = 7 × 14 = 98. Removing 28 leaves 70. Average of remaining six numbers = 70 ÷ 6 = 11.67.
317
The average of the first 20 natural numbers is:
Answer:
10.5
Average of consecutive numbers = (first + last) ÷ 2. For numbers 1 to 20: (1 + 20) ÷ 2 = 10.5.
318
The average of three numbers is 30. If one number is 20 and another is 40, what is the third number?
Answer:
30
Total of three numbers = 3 × 30 = 90. Known numbers sum = 20 + 40 = 60. Third number = 90 − 60 = 30.
319
The average of 10 numbers is 15. If each number is increased by 5, what will be the new average?
Answer:
20
When the same value is added to each number, the average increases by that value. New average = 15 + 5 = 20.
320
The average of 5 numbers is 20. If a new number is included, the average becomes 22. What is the new number?
Answer:
32
Sum of first 5 numbers = 5 × 20 = 100. New total for 6 numbers = 6 × 22 = 132. New number = 132 − 100 = 32.