Logical Reasoning

PT21 · S2 · Q10 The increase in the price of jet

A free, expert breakdown of this official LSAT Logical Reasoning question.

  • Save & drill this skill — build targeted practice sets from questions like this one

  • Video walkthroughs — watch every question solved step by step

  • 81 official LSATs — as questions, timed sections & full-length tests

Start practicing free

The increase in the price of jet fuel is due to a sharp decrease over the past year in the supply of jet fuel available relative to demand.

Statements

Over the past year, there is a lower supply of jet fuel relative to demand, which caused an increase in the price of jet fuel.

But the supply of jet fuel available for sale is larger today than it was last year.

Evaluate

Because both statements are comparative / mathematical, the inference will probably also have a comparative / mathematical feel.

We can infer by combining these two claims that the demand for jet fuel is higher now than it was a year ago.

This fact-set is analogous to this: The ratio of females to males at University X has gone down this past year. Nonetheless, there are more females at University X this year than last year.

This would show that there are more males at University X this year.

The idea of ratio or "supply relative to demand" is talking about a relationship, not an absolute number.

Let's say that last year the demand for jet fuel was 2000 barrels, and our supply was 1500 barrels. The supply of jet fuel relative to demand would be 15/20, or 3/4, or 75%.

The information here is saying that over the past year there was a decrease in the supply of fuel relative to demand, so if supply used to be 75% of demand, then now it's something lower like 50% of demand.

But there is also more jet fuel available.

If there was 1500 barrels before, maybe there is 2000 barrels now. And if supply is now 50% of demand, that would mean that there's a demand for 4000 barrels.

In other words, Last year This Year

supply 1500 2000

demand 2000 4000

supply, relative 75% 50% to demand

Goal

Look for something like, .

10.

If the statements above are true, which one of the following conclusions can be properly drawn on the basis of them?

  1. Correct

    The demand for jet fuel

    Why this is right

    As we discussed above, since supply is higher this year, but supply relative to demand is lower this year, that proves that demand must have increased even more than supply increased.

    Skill tested: Must be True · how this choice captures the argument's function is the move to repeat next time.

    72% picked this

  2. The fuel efficiency of jet

    Out of Scope: efficiency of engines

    The passage is never talking about how much jets are used, so we have no way to judge the efficiency of the engines.

    7% picked this

  3. The number of jet airline

    Out of Scope: number of flights

    We have no information about number of flights. This is just speculating a backstory for why there is more fuel available, but there could be 15 possible explanations. None of them must be true.

    13% picked this

  4. The cost of refining petroleum

    Out of Scope: cost of refining

    We don't have any information about refining costs. This would just be speculating some reason for why supply has gone up or supply relative to demand has gone down.

    2% picked this

  5. The supply of petroleum available

    Out of Scope: petroleum

    We never discuss petroleum, so we can't derive any must be true inference about it.

    5% picked this

Continue the review in LSAT Lab

Save this question, watch the video walkthrough, and drill similar questions in your LSAT Lab account.

Save and practice this skill
LSAT Lab

Turn this review into a targeted study plan.

Save this question, drill more like it, watch the video walkthrough, and track your progress in your LSAT Lab account.

Start practicing free