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
11
A tank is filled by two pipes in 20 min and 21 min respectively, and drained by a third pipe in 30 min. How long to fill the tank if all operate together?
Answer:
15.56
Step-by-step solution: 1. Filling rates: 1/20 + 1/21. 2. Draining rate: 1/30. 3. Net rate = 1/20 + 1/21 - 1/30 = 0.0643 tank/min. 4. Time = 1 / net rate = 15.56 minutes.
12
A tank is filled by two pipes in 18 min and 20 min respectively, and drained by a third pipe in 30 min. How long to fill the tank if all operate together?
Answer:
13.85
Step-by-step solution: 1. Filling rates: 1/18 + 1/20. 2. Draining rate: 1/30. 3. Net rate = 1/18 + 1/20 - 1/30 = 0.0722 tank/min. 4. Time = 1 / net rate = 13.85 minutes.
13
A tank is filled by two pipes in 20 min and 25 min respectively, and drained by a third pipe in 30 min. How long to fill the tank if all operate together?
Answer:
17.65
Step-by-step solution: 1. Filling rates: 1/20 + 1/25. 2. Draining rate: 1/30. 3. Net rate = 1/20 + 1/25 - 1/30 = 0.0567 tank/min. 4. Time = 1 / net rate = 17.65 minutes.
14
A tank is filled by two pipes in 16 min and 24 min respectively, and drained by a third pipe in 30 min. How long to fill the tank if all operate together?
Answer:
14.12
Step-by-step solution: 1. Filling rates: 1/16 + 1/24. 2. Draining rate: 1/30. 3. Net rate = 1/16 + 1/24 - 1/30 = 0.0708 tank/min. 4. Time = 1 / net rate = 14.12 minutes.
15
A tank is filled by two pipes in 16 min and 21 min respectively, and drained by a third pipe in 34 min. How long to fill the tank if all operate together?
Answer:
12.39
Step-by-step solution: 1. Filling rates: 1/16 + 1/21. 2. Draining rate: 1/34. 3. Net rate = 1/16 + 1/21 - 1/34 = 0.0807 tank/min. 4. Time = 1 / net rate = 12.39 minutes.
16
A tank is filled by two pipes in 18 min and 21 min respectively, and drained by a third pipe in 31 min. How long to fill the tank if all operate together?
Answer:
14.1
Step-by-step solution: 1. Filling rates: 1/18 + 1/21. 2. Draining rate: 1/31. 3. Net rate = 1/18 + 1/21 - 1/31 = 0.0709 tank/min. 4. Time = 1 / net rate = 14.1 minutes.
17
A tank is filled by two pipes in 20 min and 26 min respectively, and drained by a third pipe in 31 min. How long to fill the tank if all operate together?
Answer:
17.79
Step-by-step solution: 1. Filling rates: 1/20 + 1/26. 2. Draining rate: 1/31. 3. Net rate = 1/20 + 1/26 - 1/31 = 0.0562 tank/min. 4. Time = 1 / net rate = 17.79 minutes.
18
A tank is filled by two pipes in 16 min and 20 min respectively, and drained by a third pipe in 31 min. How long to fill the tank if all operate together?
Answer:
12.46
Step-by-step solution: 1. Filling rates: 1/16 + 1/20. 2. Draining rate: 1/31. 3. Net rate = 1/16 + 1/20 - 1/31 = 0.0802 tank/min. 4. Time = 1 / net rate = 12.46 minutes.
19
A tank is filled by two pipes in 16 min and 23 min respectively, and drained by a third pipe in 34 min. How long to fill the tank if all operate together?
Answer:
13.06
Step-by-step solution: 1. Filling rates: 1/16 + 1/23. 2. Draining rate: 1/34. 3. Net rate = 1/16 + 1/23 - 1/34 = 0.0766 tank/min. 4. Time = 1 / net rate = 13.06 minutes.
20
A tank is filled by two pipes in 18 min and 24 min respectively, and drained by a third pipe in 32 min. How long to fill the tank if all operate together?
Answer:
15.16
Step-by-step solution: 1. Filling rates: 1/18 + 1/24. 2. Draining rate: 1/32. 3. Net rate = 1/18 + 1/24 - 1/32 = 0.0660 tank/min. 4. Time = 1 / net rate = 15.16 minutes.