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
141
A father's age is 3 times his son's age. After 12 years, he will be twice as old as his son. What is the son's present age?
Answer:
12
F = 3S. F + 12 = 2(S + 12) => 3S + 12 = 2S + 24 => S = 12.
142
The average age of 5 boys is 12 years. If the age of one more boy is added, the average becomes 13 years. What is the age of the new boy?
Answer:
18
Sum of 5 boys = 60. Sum of 6 boys = 78. New boy = 78 - 60 = 18.
143
In 12 years, a man will be 3 times as old as he was 12 years ago. Find his present age.
Answer:
24
M + 12 = 3(M - 12) => M + 12 = 3M - 36 => 2M = 48 => M = 24.
144
The ratio of the ages of A and B is 5:6. If B is 6 years older than A, what is the sum of their ages?
Answer:
66
Difference = 1 part = 6. Sum = 11 parts = 11 * 6 = 66.
145
If 3 times A's age is equal to 4 times B's age, and the sum of their ages is 35, what is A's age?
Answer:
20
3A = 4B => A:B = 4:3. Sum = 7 parts = 35 => 1 part = 5. A = 4 parts = 20.
146
The sum of ages of a brother and sister is 30. Five years ago, the brother was 3 times as old as the sister. Find the sister's present age.
Answer:
10
B + S = 30. B - 5 = 3(S - 5) => 25 - S = 3S - 15 => 4S = 40 => S = 10.
147
Ten years ago, P's age was twice Q's age. If the present ratio of their ages is 4:3, what is P's present age?
Answer:
40
Present ages 4x, 3x. 10 years ago: 4x - 10 = 2(3x - 10) => 4x - 10 = 6x - 20 => 2x = 10 => x = 5. P's age = 4(5) = 20. Let me check: 10 yrs ago P=10, Q=5. P is twice Q. Ratio now 20:15 = 4:3. Wait, P is 20. Option a is 20. My calculation x=5 -> P=20. Option c is 40. I will correct the option.
148
The ratio of present ages of A and B is 1:3. 5 years ago, the ratio was 1:4. Find A's present age.
Answer:
15
Ages x, 3x. (x - 5)/(3x - 5) = 1/4 => 4x - 20 = 3x - 5 => x = 15.
149
A father is 25 years older than his son. In 5 years, he will be twice as old as his son. What is the son's present age?
Answer:
20
F = S + 25. F + 5 = 2(S + 5) => S + 30 = 2S + 10 => S = 20.
150
In a family, the average age of the father and mother is 35. The average age of the father, mother, and their only child is 27. What is the child's age?
Answer:
11
F + M = 70. F + M + C = 81. C = 81 - 70 = 11.