For a ten–month period, the total monthly sales of new cars within the country of Calistan remained constant. During...

Emil-Kunkin on June 5, 2022

Hi AJcaviness,

I think the first thing to focus on for a long and complex question like this would be to read the entire thing carefully, and make sure you understand as you read. Since there are so many moving parts here, this question is a decent candidate for a diagram, if you find that writing down a diagram helps to reinforce your understanding of the argument.

Personally, I might not do a diagram per se, but would probably jot down some notes to reinforce my understanding.

We are told that total sales in a country remained constant over a period of time, and that the sales and market share of MAC doubled. After this period, a new regulation was passed and MAC's market share declined, although the number of cars remained constant.

The first part of this scenario seems fairly straightforward- the total market did not change for 10 months but MAC increased their share and sales, but after the emissions standards were imposed, something changed. While the total number of cars MAC sold stayed the same, their market share decreased.

From this, we can determine that the overall market increased, but MAC's sales did not. If, for example, a company sells 50 cars a month and has half of the market, the market is 100 cars a month. If next month the company has only 33 percent of the market, but still sells 50 cars, we know the market has increased to 150 cars a month.

This shows why A is correct- it is impossible that MAC's competitors sold fewer cars after the regulation than they did before, because the market must have grown.

In addition to reading carefully and working to understand what you have read, whenever the question of total VS percent change comes into play, I like to make a little example like above, usually using round numbers like 10, 50 or 100.