LEAB Deductive and Inductive Reasoning 2 — Questions and Answers
Question 1: All robbery suspects must be interviewed before being released. Jones is a robbery suspect. Which conclusion is MOST logically supported?
- Jones must be interviewed before being released (Correct answer)
- Jones will be charged with robbery
- Jones has a prior criminal record
- Jones will be detained overnight
Correct answer: Jones must be interviewed before being released
The universal rule applies to all members of the category, and Jones belongs to that category, so the rule applies directly to him.
Question 2: If a building has been broken into, at least one point of entry will show signs of forced access. Investigators found no signs of forced access at the warehouse. What can be concluded?
- The warehouse was not broken into (Correct answer)
- The perpetrator had a key
- The evidence was destroyed
- The break-in occurred through the roof
Correct answer: The warehouse was not broken into
The contrapositive of 'if break-in then forced entry' is 'if no forced entry then no break-in,' which applies here.
Question 3: The suspect either entered through the front door or the back window. Forensic evidence confirms the front door was not used. What conclusion logically follows?
- The suspect entered through the back window (Correct answer)
- The suspect used a key
- There was an accomplice inside
- The evidence is inconclusive
Correct answer: The suspect entered through the back window
When one of two mutually exclusive options is ruled out by evidence, the other must be true.
Question 4: If Officer Reyes is working the night shift, his patrol car will be in the parking lot. His patrol car is not in the lot. What can be concluded?
- Officer Reyes is not working the night shift (Correct answer)
- Officer Reyes is on an active call
- The patrol car is being repaired
- Officer Reyes is working a different beat
Correct answer: Officer Reyes is not working the night shift
Modus tollens: if P implies Q and Q is false, then P must be false.
Question 5: No officer may carry a department-issued firearm without completing annual qualification. Detective Park has not completed annual qualification. What logically follows?
- Detective Park may not carry a department-issued firearm (Correct answer)
- Detective Park is suspended from active duty
- Detective Park must retake the test immediately
- Detective Park may carry a personal firearm instead
Correct answer: Detective Park may not carry a department-issued firearm
The universal prohibition applies to all officers; Detective Park falls under that rule and cannot carry the firearm.
Question 6: Whenever there is a large crowd, pickpockets operate. Whenever pickpockets operate, officers must deploy undercover agents. There is a large crowd downtown. What must follow?
- Officers must deploy undercover agents downtown (Correct answer)
- Pickpockets are already in custody downtown
- The crowd will disperse on its own
- Additional uniformed officers will be called downtown
Correct answer: Officers must deploy undercover agents downtown
Chaining the two conditional rules—crowd leads to pickpockets, pickpockets require undercover agents—forces the conclusion.
Question 7: It is false that all witnesses at the scene were uncooperative. What can be concluded?
- At least one witness at the scene was cooperative (Correct answer)
- All witnesses at the scene were cooperative
- Most witnesses at the scene were cooperative
- No witnesses at the scene were uncooperative
Correct answer: At least one witness at the scene was cooperative
Negating the universal statement 'all were uncooperative' yields the existential claim that at least one was not uncooperative.
LEAB Deductive and Inductive Reasoning 2
All robbery suspects must be interviewed before being released.
Jones is a robbery suspect.
Which conclusion is MOST logically supported?