CCTST Deductive Reasoning 2

Question 1

All mammals are warm-blooded. No reptiles are warm-blooded. Which conclusion must follow?

Accepted Answer

No reptiles are mammals

Answer

Since all mammals are warm-blooded and no reptiles are warm-blooded, no reptile can be a mammal.

Question 2

If it is raining, the ground is wet. The ground is not wet. What must be true?

Accepted Answer

It is not raining

Answer

This is modus tollens: denying the consequent (ground not wet) allows us to deny the antecedent (not raining).

Question 3

Every student who passed the exam studied for at least five hours. Mia did not study for five hours. What can be concluded?

Accepted Answer

Mia did not pass the exam

Answer

Because studying five or more hours is necessary to pass, failing to meet that condition means Mia could not have passed.

Question 4

All A are B. All B are C. Which statement is necessarily true?

Accepted Answer

All A are C

Answer

The chain All A→B and All B→C yields All A→C by the hypothetical syllogism.

Question 5

Either the server is down or the network is broken. The network is not broken. What follows?

Accepted Answer

The server is down

Answer

Disjunctive syllogism: when one disjunct is false, the other must be true.

(CCTST) California Critical Thinking Skills Test Practice Test