gmattesttaker2 wrote:Hello,
Can you please assist with this IR question? The solution to question no. 2 is clear but I am not clear with the solution to question 1. Thanks - Sri

Dear Gmattesttaker2,
What you are asking is a great question, and I am happy to help.

I believe your question arises from a common error associated with percents. Suppose the price of something begins at $30, then goes up to $60, then goes back to $30. The dollar-amounts of the increase and the decrease are, of course, identical, BUT the percent increase & decrease are NOT the same. The increase, from $30 to $60, doubles the starting amount ($30), so it's a 100% increase. The decrease, from $60 to $30, cuts the starting amount ($60) in half, so it's a 50% decrease. Thus, the increase from $30 to $60 is a bigger percent change than the decrease from $60 to $30, even though those two changes are the exact same dollar amount.

In the same way ---- the category "Low-fat milk (1%) and skim milk" approximately doubles, so that's about a 100% decrease. The category "Plain whole milk" is approximately cut in half over this time period, so that's about a 50% decrease. 100 > 50, so the former has a bigger percent change.

As a general rule, if you increase & decrease by the same amount (in terms of actually number or price or gallons of milk or whatever), then the increase will be a larger percent value, because an increase starts with a smaller starting value, whereas a decrease starts with a larger starting value, and percent change is ALWAYS a percent of the starting value.

For more on percent & percent changes, see this blog:
https://magoosh.com/gmat/2012/understand ... -the-gmat/

Does this answer your question?
Mike