LSAT 105 | Section 2 | Logical Reasoning: Q24

LR Question 24 Explanation

QUESTION TEXT: Each December 31 in Country Q, a tally is made of the…

QUESTION TYPE: Must be True

FACTS:

1. No coal has gone in or out of the country since 1970.
2. The country had smaller coal reserves in 1991 than in 1990.

ANALYSIS: The wording is dense, but the concept is simple. In 1991 the country used more coal than it mined, so its coal stocks went down.

It’s useless to make comparisons between years. The measurements were taken on Deccember 31 1990, and December 31, 1991. All of the relevant change happened between those dates. The rest of 1990 is irrelevant, but 1990 is mentioned in all of the wrong answers!

Here’s an example of what happened. At the start of the year, we have 1,000,000 tons of coal (for example) and at the end we had 900,000 tons (for example). We don’t know how much we mined, but we do know we used more than we mined.

Some people find this question very difficult, so I’ll use a second example.

You can pretend coal is your debt/savings. If at the start of the year you had $5,000 saved and at the end you had $4,000 then you must have spent more than you earned. I have no idea how much you earned. It could have been $1,000,000 or $0. All I know is that you spent $1,000 more than whatever you earned.

___________

1. Year 1990 is irrelevant for why coal stocks changed during 1991.
2. CORRECT. This is what caused stocks to fall. Country Q took out more coal from the stock than they put in.
3. Year 1990 is irrelevant. The relevant changed happened in 1991.
4. We have no clue what the amount of coal consumed was, except that it was higher than the amount consumed in 1991. 1990 is irrelevant.
5. Same as the other answers. 1990 is irrelevant. And there’s no reason to focus on the first half of either year.

Recap: The question begins with “Each December 31 in Country Q, a tally is made of the”. It is a Must be True question. Learn more about LSAT MBT questions in our guide to LSAT Logical Reasoning question types.