Analytical Reasoning

The argument uses modus tollens: If Tom is guilty, then he was at the scene. Since Tom was not at the scene, it logically follows that Tom is not guilty.

The statement "Only citizens can vote" means that voting implies citizenship. Since Maria voted, it logically follows that Maria is a citizen.

This question illustrates modus tollens: given 'If A then B' and 'B is false', we conclude 'A is false' because if A were true, B would have to be true, which contradicts the given information.

The premises state that no fish can walk and that sharks are fish. Therefore, it logically follows that sharks cannot walk, making option C the valid conclusion.

The premise states that every student who studies passes the exam. Since John did not pass, by modus tollens, we conclude John did not study. Other options contradict the premise or introduce unsupported assumptions.

Given P → Q and Q → R, by hypothetical syllogism, we have P → R. Since P is true, R must also be true.

The statement 'If it rains, the ground gets wet' is a conditional statement. Observing that the ground is wet does not guarantee that it rained, as other causes could have made the ground wet. This is an example of the logical fallacy called affirming the consequent, so the correct conclusion is that it may or may not have rained.

The question uses disjunctive syllogism: since either the butler or the maid stole the jewel, and the maid has an alibi (is not guilty), it logically follows that the butler must have stolen the jewel.

Since no politician is honest and some leaders are politicians, those leaders who are politicians must be dishonest. Therefore, it follows that some leaders are not honest.

The series is supposed to increase by successive square numbers added to each term: +1, +4, +9, +16, +25, ... Starting from 15: 15 + 1 = 16, 16 + 4 = 20, 20 + 9 = 29, 29 + 16 = 45, 45 + 25 = 70. The given series is 15, 16, 20, 30, 45, 70. The term 30 is incorrect because it breaks the pattern; it should be 29 instead of 30.