Problem Solving

Hey California,

Unfortunately, this is not a badly worded question. I think you're misreading it. If you take away half of something multiple times, you cannot reset it to its original value. In other words:

You have $10. Take away half.

Now you have $5. Take away half.

At this point, you do not still have $10. You can't reset the meaning of "half" back to where you started.

-t

Here's something that I ask my GMAT students all the time: do you want to be right, or do you want to get a good score?

Of course you're right - balloons in the real world do not behave that way. Nor do populations of bacteria double exactly in size precisely once per hour. The point is not to analyze whether these situations make sense. The point is to apply basic mathematical principles to the given situations.

Here, the test writer wanted to test the idea of successive proportion change in a word problem format. There aren't many real-world situations that would exactly fit the kind of relationship they're describing here, so the writer made one up. I agree that the question could probably be written in a more straightforward way, but it never helps to be too nit-picky.

Your examples aren't necessarily showing the same principle. "Half the lap" in this instance would be half the total each time, whereas "half the air" in the balloon question can be understood to mean half the remaining air. The first is not successive; the second is. This question couldn't be an amortization question unless it specified "half of the original air" or actually used the word amortization.

You'll run across a lot of GMAT problems that seem poorly worded, or not real-world true (such as apples costing $0.05, or rooms only taking 2 hrs to paint!). If you obsess over those details, you miss the bigger picture. Start by asking - what concept is the test writer getting at here? If you can identify the test-writer's objective, it can help prevent over-thinking.