Reasoning

Correct answer: D

Exactly one excludes simultaneous selection.

Correct answer: C

I is correct: All A are B. No B are C. → No A are C. Every A lies in B, which is disjoint from C. II is incorrect: If it rains, play stops. Play continued without stopping. → It did not rain during that play. The stated conditional rules out rain when its consequence is absent.

Correct answer: D

This is the valid contrapositive of the conditional.

Correct answer: A

I is incorrect: All A are B. No B are C. → No A are C. Every A lies in B, which is disjoint from C. II is incorrect: Some inspectors on the list are engineers. No engineer on the list is absent. → Some inspectors on the list are present. The inspectors who are listed engineers cannot be absent.

Correct answer: D

The inclusive disjunction requires B when A is absent.

Correct answer: A

I is correct: All roses in a box are red. This flower is a rose in that box. → This flower is red. The universal statement applies to the specified rose. II is incorrect: All archived files are indexed. Some letters are archived files. → Some letters are indexed. The archived letters fall within the indexed class.

Correct answer: C

I is incorrect: If a switch is on, a lamp glows. The lamp does not glow. → The switch is not on. This is the valid contrapositive of the conditional. II is correct: All keys in drawer A open lock L. Key K is in drawer A. → Key K opens lock L. K falls under the universal rule.

Correct answer: D

A flexible token cannot belong to the excluded class.

Correct answer: A

I is correct: Some buses here are electric. No electric vehicle here uses diesel. → Some buses here do not use diesel. The electric buses belong to the non-diesel category in the stated setting. II is correct: Some A are B. All B are C. → Some A are C. The A that are B must also be C.

Correct answer: C

I is correct: All P are Q. Some Q are R. → No definite P-R overlap is established. The Q that are R may all lie outside P. II is incorrect: At least one of A and B attends. A does not attend. → B attends. The inclusive disjunction requires B when A is absent.

Correct answer: A

The archived letters fall within the indexed class.

Correct answer: B

I is correct: All roses in a box are red. This flower is a rose in that box. → This flower is red. The universal statement applies to the specified rose. II is correct: All A are B. No B are C. → No A are C. Every A lies in B, which is disjoint from C.

Correct answer: A

Every A lies in B, which is disjoint from C.

Correct answer: C

I is incorrect: If a switch is on, a lamp glows. The lamp does not glow. → The switch is not on. This is the valid contrapositive of the conditional. II is incorrect: All archived files are indexed. Some letters are archived files. → Some letters are indexed. The archived letters fall within the indexed class.

Correct answer: D

The Q that are R may all lie outside P.

Correct answer: A

I is incorrect: All A are B. No B are C. → No A are C. Every A lies in B, which is disjoint from C. II is incorrect: If a switch is on, a lamp glows. The lamp does not glow. → The switch is not on. This is the valid contrapositive of the conditional.

Correct answer: C

I is correct: Some A are B. All B are C. → Some A are C. The A that are B must also be C. II is correct: All P are Q. Some Q are R. → No definite P-R overlap is established. The Q that are R may all lie outside P.

Correct answer: B

The A that are B must also be C.

Correct answer: A

I is correct: All A are B. No B are C. → No A are C. Every A lies in B, which is disjoint from C. II is incorrect: All archived files are indexed. Some letters are archived files. → Some letters are indexed. The archived letters fall within the indexed class.

Correct answer: A

Take east as positive: 11 − 4 + 4.

Correct answer: B

I is correct: 2,3,5,8,13,... with each term the sum of the preceding two → 21. 8+13=21. II is correct: 2,6,12,20,30,... with nth term n(n+1) → 42. The sixth term is 6×7.

Correct answer: A

The next pair uses E and V.

Correct answer: C

I is incorrect: A,C,F,J,O,... using alphabet positions with increments 2,3,4,5,... → U. Positions 1,3,6,10,15 are followed by 21. II is incorrect: 5,7,11,13,17,... as consecutive primes starting at five → 19. Nineteen is the next prime after seventeen.

Correct answer: A

47×2+1=95.

Correct answer: C

I is incorrect: 2,5,10,17,26,... with successive positive odd increments → 37. The increments are 3,5,7,9, then 11. II is correct: 64,32,16,8,... with repeated halving → 4. 8/2=4.