GMAT Review Diagnostic Quantitative Question 1

by Chuck on Sunday, 20 March, 2011

Question 1 page 20

The key word here is ‘equivalent’. The total payable can be expressed as a sum with two parts:

5(3.99) + 15.95

and each of the answers uses the same format. Now logically, any answer which contains one part the same and the other part different (whether larger or smaller) must add to a different amount. Hence B is incorrect, and after we calculate the sum in the brackets, D and E are incorrect too.

Moreover, any answer which contains EITHER both parts bigger OR both parts smaller must also be incorrect. Hence C is incorrect and by elimination A must be correct.

The correct answer must either have both parts the same, which is unlikely, or one part larger and one part smaller by the same amount. Double-checking with A gives the first part 5¢ larger (1¢ for each of five compact discs) and the second part 5¢ smaller.

Strategy tip

Don’t do any calculations you don’t need to do. You may be able to see that amounts must be equivalent – equal in value – without knowing what those amounts actually are. This is often the case in the Data Sufficiency section where it is enough to know that a value can be deduced rather than to have to actually calculate it.

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