Logical Reasoning Test Practice Course: Deductive reasoning and syllogisms

1. Pergunta 1 de 18

   All guards at the site have a first-aid certificate. Priya is a guard at the site. Which statement must be true?

   • ASome people with a first-aid certificate are not guards at the site
   • BEveryone with a first-aid certificate is a guard at the site
   • CPriya has a first-aid certificate
   • DPriya does not have a first-aid certificate
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   Resposta: C. Priya has a first-aid certificate

   Priya belongs to the group "guards at the site", and everyone in that group has the certificate. The statements say nothing about people outside the group.

2. Pergunta 2 de 18

   No vehicle in the north yard is a rental. The blue van is in the north yard. Which statement must be true?

   • AThe blue van is a rental
   • BSome rentals are in the north yard
   • CEvery rental is in the north yard
   • DThe blue van is not a rental
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   Resposta: D. The blue van is not a rental

   Nothing in the north yard is a rental, and the blue van is in the north yard, so it cannot be a rental.

3. Pergunta 3 de 18

   If the fire alarm sounds, everyone leaves the building. The fire alarm sounded. Which statement must be true?

   • ANot everyone left the building
   • BThe alarm was a drill
   • CEveryone left the building
   • DThe alarm did not sound
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   Resposta: C. Everyone left the building

   The "if" part happened, so the "then" part must follow. This form is called modus ponens.

4. Pergunta 4 de 18

   All trainees attend the safety briefing. Everyone who attends the safety briefing signs the attendance sheet. Which statement must be true?

   • AEveryone who signs the attendance sheet is a trainee
   • BAll trainees sign the attendance sheet
   • CSome people at the briefing are not trainees
   • DSome trainees do not sign the attendance sheet
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   Resposta: B. All trainees sign the attendance sheet

   This is a chain: trainees are inside the briefing group, which is inside the signing group. So all trainees sign. The reverse is not stated.

5. Pergunta 5 de 18

   Each shipment goes either by truck or by rail, but not both. Shipment 12 did not go by rail. Which statement must be true?

   • AShipment 12 went by truck
   • BShipment 12 did not go by truck
   • CShipment 12 went by rail
   • DShipment 12 went by both truck and rail
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   Resposta: A. Shipment 12 went by truck

   There are only two choices. Rail is ruled out, so it must be truck.

6. Pergunta 6 de 18

   All forklift operators wear steel-toe boots. Sam wears steel-toe boots. What can you conclude about Sam?

   • AEveryone who wears steel-toe boots is a forklift operator
   • BSam is not a forklift operator
   • CSam is a forklift operator
   • DThe statements do not say whether Sam is a forklift operator
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   Resposta: D. The statements do not say whether Sam is a forklift operator

   The rule only goes one way: operators wear boots. Other people may wear boots too, so Sam may or may not be an operator.

7. Pergunta 7 de 18

   If a delivery arrives before noon, Lee signs for it. Lee did not sign for today's delivery. Which statement must be true?

   • ALee signs for every delivery
   • BToday's delivery did not arrive before noon
   • CToday's delivery arrived before noon
   • DSomeone else signed for today's delivery
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   Resposta: B. Today's delivery did not arrive before noon

   If it had arrived before noon, Lee would have signed. Lee did not sign, so it did not arrive before noon. This form is called modus tollens.

8. Pergunta 8 de 18

   Some cashiers are students. All students get a transit discount. Which statement must be true?

   • ASome cashiers get a transit discount
   • BSome students are not cashiers
   • CAll cashiers get a transit discount
   • DNo cashier gets a transit discount
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   Resposta: A. Some cashiers get a transit discount

   The cashiers who are students must get the discount, because every student does. Nothing is said about the other cashiers.

9. Pergunta 9 de 18

   A visitor may enter the lab only if they wear safety glasses. Which statement must be true?

   • AAny visitor wearing safety glasses enters the lab
   • BA visitor who stays out of the lab is not wearing safety glasses
   • CA visitor who enters the lab is wearing safety glasses
   • DA visitor without safety glasses enters the lab
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   Resposta: C. A visitor who enters the lab is wearing safety glasses

   "A only if B" means "if A, then B". Wearing glasses is required to enter, but it does not guarantee entry.

10. Pergunta 10 de 18

    If a badge has expired, the door will not open. The door did not open for Mia. What can you conclude?

    • AMia's badge has expired
    • BMia's badge has not expired
    • CThe door opened for Mia
    • DThe statements do not say whether Mia's badge has expired
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    Resposta: D. The statements do not say whether Mia's badge has expired

    The door could stay shut for other reasons. Concluding the badge expired is the mistake called affirming the consequent.

11. Pergunta 11 de 18

    Some of the new hires speak French. Which statement must be true?

    • ASome new hires do not speak French
    • BAt least one new hire speaks French
    • CNo new hire speaks French
    • DAll new hires speak French
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    Resposta: B. At least one new hire speaks French

    "Some" means at least one, and possibly all. It does not tell you that some new hires do not speak French.

12. Pergunta 12 de 18

    All night-shift staff have a parking pass. Some cleaners do not have a parking pass. Which statement must be true?

    • ANo cleaners work the night shift
    • BSome people with a parking pass are not cleaners
    • CSome cleaners are not night-shift staff
    • DSome night-shift staff are cleaners
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    Resposta: C. Some cleaners are not night-shift staff

    A cleaner without a pass cannot be on the night shift, because every night-shift worker has a pass. Other cleaners might still work nights.

13. Pergunta 13 de 18

    No contractor has a staff badge. All the people in Room 4 are contractors. Which statement must be true?

    • ASome people with a staff badge are in Room 4
    • BSome people in Room 4 have a staff badge
    • CNo one in Room 4 has a staff badge
    • DAll contractors are in Room 4
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    Resposta: C. No one in Room 4 has a staff badge

    Everyone in Room 4 is a contractor, and no contractor has a staff badge, so no one in Room 4 has one.

14. Pergunta 14 de 18

    The store opens at 9 a.m. unless it is a holiday. Today the store did not open at 9 a.m. Which statement must be true?

    • AThe store opened at 10 a.m.
    • BThe store opens at 9 a.m. every day
    • CToday is not a holiday
    • DToday is a holiday
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    Resposta: D. Today is a holiday

    "A unless B" means "if not B, then A". If it were not a holiday, the store would have opened at 9. It did not, so it is a holiday.

15. Pergunta 15 de 18

    Some drivers are mechanics. Some mechanics are supervisors. Which statement must be true?

    • ANo drivers are supervisors
    • BAll supervisors are mechanics
    • CSome drivers are supervisors
    • DSome mechanics are drivers
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    Resposta: D. Some mechanics are drivers

    "Some drivers are mechanics" can be turned around: some mechanics are drivers. Two "some" statements tell you nothing certain about drivers and supervisors.

16. Pergunta 16 de 18

    Which of these arguments is valid?

    • AIf it snows, the crew salts the lot. The crew salted the lot. So it snowed.
    • BIf it snows, the crew salts the lot. The crew did not salt the lot. So it did not snow.
    • CIf it snows, the crew salts the lot. The crew salted the lot. So it did not snow.
    • DIf it snows, the crew salts the lot. It did not snow. So the crew did not salt the lot.
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    Resposta: B. If it snows, the crew salts the lot. The crew did not salt the lot. So it did not snow.

    Only the first one is valid: if snow always leads to salting, no salting means no snow. The others assume the rule works backwards.

17. Pergunta 17 de 18

    If a ticket is high priority, it goes to Level 2. If a ticket goes to Level 2, a manager is told. No manager was told about Ticket 88. Which statement must be true?

    • AA manager was told about Ticket 88
    • BTicket 88 is high priority
    • CTicket 88 is not high priority
    • DTicket 88 went to Level 2
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    Resposta: C. Ticket 88 is not high priority

    Work backwards along the chain: no manager told means it did not go to Level 2, and that means it was not high priority.

18. Pergunta 18 de 18

    All inspectors are engineers. No engineer works part time. Some part-time workers are students. Which statement must be true?

    • ASome students are inspectors
    • BNo student is an engineer
    • CNo inspector works part time
    • DAll engineers are inspectors
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    Resposta: C. No inspector works part time

    Inspectors are a group inside engineers, and no engineer works part time, so no inspector does. The student statement does not change this.

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