Bunuel wrote:

The ratio of television sets to radios at an electronics store before a new shipment arrives is 12:7. If no television sets or radios leave the store, and the only television sets and radios that arrive are in the new shipment, what is the ratio of television sets to radios after the new shipment arrives?

(1) The new shipment contains 132 television sets.

(2) The new shipment contains 77 radios.

Kudos for a correct solution.

This question is a caveat to blindly following the much hyped strategy of DS questions - if you can establish the sufficiency, do not solve the question.

There are cases where you need to look carefully before deciding whether the sufficiency condition is actually met. Some of them are:

1. Quadratic equations - Ensure that the roots are not the same. If they are the same, there could be a unique solution though you may not expect it.

2. Solving simultaneous equations - Ensure that the equations are not the same (e.g. one is a multiple of the other). There is no unique solution in this case.

3. Ratios - Ensure that the ratios are not the same. If they are, when you add them, the ratio stays the same.

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Karishma

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