Logical reasoning-based questions are not at all difficult to tackle if one has a basic understanding of the types of questions asked.The accuracy is highest in such questions, and the time spent solving them can be quite less if one has done a good amount of practice.

The questions that are asked in logical reasoning require one to find out whether the given conclusion is valid or not.

For example:

1. All drunken drivers meet with an accident.
Salman is a drunken driver.
Conclusion – Salman will meet with an accident

This one is pretty straightforward. Since Salman belongs to a group, all members of which meet with an accident, he would meet with an accident.

E.x. 2. Most males are intelligent.
Mr. X is a male
Conclusion – Mr. X may or may not be intelligent

Here there are two possibilities. Either Mr. X is a part of the group of intelligent males or he is not. Hence, it follows that he may or may not be intelligent.
In the exam the questions that are asked have two statements followed by two conclusions and you have to determine which conclusion is correct. Obviously the questions are not so easy as the above examples and may require one to draw venn diagrams to solve the questions. E.g.

1.    Statements –
some students are smart
all students are hardworking

Conclusions – (i) some hardworking students are smart
(ii) some smart students are hardworking
Solution – Both the conclusions are correct, as some students are definitely both smart and hardworking.

2.    Statement–
tennis players get married only to models

Conclusions – (i) Madhu is married to a tennis player
(ii) Madhu is not married to a tennis player
Solution – Here either Madhu can be married to a tennis player or to someone who is not a tennis player. So either conclusion (i) or (ii) follow but not both.

Statements –
some roses are red
some red are black.

Conclusions – (i) no black is a rose.
(ii) no rose is a black

Solution – Here both the statements are possibilities. It may be that some roses are black or no roses are black. Hence neither of the conclusions follows.

Logical Consistency:

Logical Consistency questions have a main statement followed by four answer alternatives. One of these is logically correct and consistent with the main statement. Again, speed is a crucial factor here.

For example,
Main Statement: If you are in the IIMs, you have cleared the CAT.

It is very evident that if I am in the IIMs, I have cleared CAT. Can we also conclude that if I am not in the IIMs, I have not cleared CAT? No. Is it possible for one to have cleared CAT and not be in the IIMs – YES. The statement says that if you are in the IIMs, you have definitely cleared the CAT. But one can clear CAT and choose not to be in the IIMs.

Thus the only conclusions possible are:
1.    you are in the IIMs implies you have cleared CAT.
2.    you have not cleared CAT implies you are not in the IIMs.

The main statement may have any of the following variants:
1.    if
2.    if and only if
3.    whenever
4.    either….or
5.    only when

Let us understand the difference between the “if” and “if and only if” as well as the “when” and “only when” type of questions.

Statement : If it rains, the ground is wet.
Meaning : Here the ground can be wet otherwise also, i.e. when it does not rain. But if it rains the ground is surely wet.

Statement : If and only if it rains, the ground is wet.
Meaning : Here the ground cannot be wet otherwise i.e. if the ground is wet, it must have rained. Also, it goes without saying that if it rained, the ground is wet.

Statement : When Raj studies, he gets a headache.
Meaning : Here he can get a headache otherwise also.

Statement : Only when Raj studies, he gets a headache.
Meaning : Here Raj cannot get a headache due to any reason other than studying.

The “either-or” type of question is as simple as the name suggests – either this or that e.g.
Statement : Either Sushmita or Aishwarya is beautiful
Here the conclusions can be:
1.    Sushmita is beautiful implies Aishwarya is not beautiful
2.    Aishwarya is beautiful implies Sushmita is not beautiful