Hi

For that reason I explained the problem step by step and actually sentence by sentence.

Those two changes as per the stem a two consecutive % reductions

First the dust is filtered out. Next, the grain has a starting moisture content of 28% (by weight) and so is dried to 15% moisture content (by weight).

When you see ugly decimals, like 0.28 (28%), you should be thinking how to solve this without needing to do time consuming calculations. Remember, the calculator on the GRE will slow you down.

Because the values in the answer choices are relatively similar, we should be careful “estimating” to make our calculations easier. Undoubtedly exact calculations would offer a more confident and accurate answer. But if time is against you…

Here’s how we would make the maths easier:

Dust removed: 0.2 * 1800 = 360
Moisture weight: 0.3 * 17640 = 5292 (0.28 rounded up to 0.3)
Dry weight: 17640 - 5000 = 12640 (5292 rounded down to 5000 to adjust for our rounding up)
Moisture reduced by: 30/15 = 0.5 (rounded up)
“New” moisture: 0.5 * 5000 = 2500
New corn mixture Wright: 12640 + 2500 = 15140
Add the dust: 15140 + 360 = 15500

Remember we rounded up, so we want to choose the closest answer choice that’s less than this. That would be choice (C)

I was also quite confused with the wording, and I don't see how we have two consecutive reductions. I agree with simran2007 that there must be 13% moisture left.

If we multiply 17,640 by 72%, doesn't it mean that we get rid of all the moisture content? There was 28%, and now there is none, how can we reduce it even further?