Here is the answer to yesterday's GMAT challenge (courtesy of Integrated Learning)

Answer: D

Explanation:
For the two day period in question, Companies A and B both had increases in their stock prices. The question asks us to figure out what the overall increase in stock price was for the two days, for both companies.

The best course of action here is to assume that they both start at $100. The increases would look like this:

	Start	Day 1	Day 2
A	$100	$130	$156
B	$100	$102	$153

Because we started with 100 for both companies, we can quickly see that by day two, Company A had increased by $56, or 56%, and Company B had increased by $53, or 53%. Thus, m = 56 and n = 53.

Now we simply plug in m and n to the answer choices, and D is the only one which works.

For more GMAT questions and prep tips, visit Integrated Learning.