Tackling conditional statements in Critical Reasoning questions

Tackling conditional statements in Critical Reasoning questions

Today we will take a look at conditional statements. Sometimes on the GMAT, you will come across something that looks like this:

If you go outside in the rain, then you will get wet.

This is called a conditional statement, or an “if then” statement. You are most likely to see these kinds of statements on critical reasoning: inference or draw a conclusion questions. They come in many different forms, for example:

I will play soccer on Sunday, only if my exam is cancelled.

Mary will go to the store, unless her son gets out of band practice late.

All are examples of conditional statements and can be changed to the traditional if then form:

If her son does not get out of band practice late, Mary will go to the store.

If my exam is cancelled, I will play soccer on Sunday.

Because it says “only if” you also know that this is true: If my exam is not cancelled, I will not play soccer on Sunday.

What is important to note about conditional statements is that the contrapositive is also true. The contrapositive is the same statement, but switched around and negated. So, if not A then B. The contrapositive of this would be if not B then A.

Here are the contrapositives of the previous statements:

If you are not wet, then you did not go outside in the rain

If I don’t play soccer on Saturday, then my exam was not cancelled.

If Mary did not go to the store, then her son got out of band practice late.

So if you see a prompt with a conditional statement, it is perfectly logical to infer that the contrapositive it also true. However, be careful the GMAT test makers may try to trick you, by giving another variation of the statement that is not the contrapositive but don’t be fooled!

In summary, remember that with conditional statements:

• You must learn to recognize a conditional statement and translate it to its if then form
• The only thing you can infer is the contrapositive.
• If the statement says A will happen ONLY IF B, you can also infer that if not B then not A .

Originally Published at Economist GMAT Blog
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