CLAT Logical Reasoning & Quantitative Techniques 5 — Questions and Answers
Question 1: Two pipes can fill a tank in 20 and 30 minutes respectively. A drain can empty it in 15 minutes. If all three are open together, in how many minutes will the tank be filled?
- 60 minutes
- The tank will never fill. (Correct answer)
- 120 minutes
- 45 minutes
Correct answer: The tank will never fill.
Net rate = 1/20 + 1/30 − 1/15 = 3/60 + 2/60 − 4/60 = 1/60 − 0 = −1/60, which is negative, so the drain empties faster than the pipes fill and the tank never fills.
Question 2: Argument: 'Speed limits should be abolished because experienced drivers can judge safe speeds.' Which assumption underlies this argument?
- All drivers are experienced.
- Speed limits are the only road safety measure.
- Experienced drivers' judgment is always reliable and sufficient for safety. (Correct answer)
- Speed limits cause more accidents than they prevent.
Correct answer: Experienced drivers' judgment is always reliable and sufficient for safety.
The argument assumes experienced drivers' judgment is a reliable and sufficient substitute for standardized speed limits.
Question 3: If Monday is the 15th of a month and the month has 31 days, on what day does the last day of the month fall?
- Friday
- Saturday
- Sunday (Correct answer)
- Thursday
Correct answer: Sunday
From the 15th (Monday) to the 31st is 16 days; 16 mod 7 = 2, so two days after Monday = Wednesday — wait: 15+16=31, 16 days later; Monday + 16 = Monday+2 weeks+2 days = Wednesday.
Question 4: A passage states: 'Eyewitness testimony is often unreliable due to memory distortions.' Which conclusion is best supported?
- Courts should never admit eyewitness testimony.
- Eyewitness testimony should be corroborated with additional evidence before being relied upon. (Correct answer)
- All eyewitnesses are liars.
- Memory distortions occur only under stress.
Correct answer: Eyewitness testimony should be corroborated with additional evidence before being relied upon.
The passage supports caution about eyewitness testimony, suggesting corroboration is prudent, not that it should be categorically excluded.
Question 5: Statements: All laws are rules. Some rules are guidelines. Conclusion I: Some laws are guidelines. Conclusion II: All guidelines are laws.
- Only I follows.
- Only II follows.
- Both I and II follow.
- Neither I nor II follows. (Correct answer)
Correct answer: Neither I nor II follows.
We cannot determine whether the laws that are also rules overlap with the rules that are guidelines, so neither conclusion necessarily follows.
Question 6: A person invests ₹10,000 at 10% simple interest per annum. After how many years will the total amount be ₹15,000?
- 3 years
- 4 years
- 5 years (Correct answer)
- 6 years
Correct answer: 5 years
Interest needed = ₹5,000; using SI = P×R×T/100, T = 5000×100/(10000×10) = 5 years.
Question 7: Which pattern of reasoning best describes: 'In all observed cases, contracts signed under duress were held voidable. Therefore, contracts signed under duress are always voidable.'
- Deductive reasoning
- Inductive reasoning (Correct answer)
- Abductive reasoning
- Analogical reasoning
Correct answer: Inductive reasoning
Drawing a general rule from repeated specific observations is inductive reasoning.
CLAT Logical Reasoning & Quantitative Techniques 5
Two pipes can fill a tank in 20 and 30 minutes respectively.
A drain can empty it in 15 minutes.
If all three are open together, in how many minutes will the tank be filled?