Lesson: Assumption Questions

Question link: https://gmatclub.com/forum/commentator-the-theory-of-trade-retaliation-s...

We're told that, if Country X closes some of its markets to Country Y, then Country Y should close some of it's markets to Country X.

CONCLUSION: If every country acted this way, no country would trade with any other.

Let's use the NEGATION technique:

(A) SOME countries actually act according to the theory of trade retaliation.
Does this destroy the conclusion that "If every country acted this way, no country would trade with any other"?
Not really.
If 1 or 2 countries act this way, but no other countries do, then most countries will still trade with each other.

(D) For any two countries, NEITHER country has some market closed to the other.
Does this destroy the conclusion that "If every country acted this way, no country would trade with any other"?
YES!
If no countries are closing some of their markets to other countries, then trade between countries will continue as usual.

Answer: D

Does that help?

Cheers,
Brent

Sorry, but I don't understand your question. Can you rephrase it?

Those other two assumptions are also crucial to the argument.
In fact, arguments can have lots of necessary assumptions. This is why the question stem typically asks "Which of the following is AN assumption on which the argument depends?" (as opposed to "Which of the following is THE assumption on which the argument depends?"

Assumption 1: Nothing stops the championship.
If we negate this, we get: The championship does NOT occur.
This clearly destroys the conclusion, since Juan can't win the championship if there is no championship.

Assumption 2: Juan is eligible to play in the championship.
If we negate this, we get: Juan is NOT eligible to play in the championship
This clearly destroys the conclusion, since Juan can't win the championship if he in NOT eligible to play in championship.

Does that help?

Cheers,
Brent

Link: https://gmatclub.com/forum/last-august-the-xt-chain-of-gasoline-stations...

The question stem: In evaluating the argument, it would be most helpful to answer which of the following?
This is an Evaluate the Conclusion question. More here: https://www.gmatprepnow.com/module/gmat-critical-reasoning/video/1144

The argument here is that the sales promotion (i.e., buy 10+ gallons and get free car wash) CAUSED the 10% increase in sales.
However, if it were the case that ALL gas stations (XT gas stations and non-XT gas stations) in the area saw a 10% increase, then that would seriously undermine the conclusion that the sales promotion CAUSED the 10% increase in sales.

(A) In the areas in which XT’s gasoline stations operate, how did total combined gasoline sales for all gasoline stations last August compare with sales for the previous August?

Knowing the answer to this question would help determine whether the sales promotion caused the 10% increase in sales.

Cheers,
Brent

For assumption questions, we aren't trying to identify "the answer choice that [goes] against the conclusion of the argument. We're trying to find an answer choice that is 100% necessary in order to draw the conclusion.

It's only when we apply the Negation Technique that we are looking for the answer choice that destroys the conclusion.

In this sense, Assumption questions are similar to Strengthen the Argument questions in that the correct answer choice improves the validity of the conclusion.

The only difference is that, in Assumption questions, the missing assumption is CRITICAL to the conclusion, and in Strengthen the Argument questions, the missing premise HELPS strengthen the conclusion

Does that help?

Cheers,
Brent

Question link: https://gmatclub.com/forum/sviatovin-is-a-medieval-moringian-text-whose-...

I believe that the "family composition" describes all of the relationships, children, marriages, etc. A family tree.
It's possible that some family trees note date of deaths, but that wouldn't be relevant here anyway, since the father was said to be alive when the Moringian was written. That is, at the time the Moringian was written, the father's death was still in the future.

Question link: https://gmatclub.com/forum/kitchen-magazine-plans-to-license-the-use-of-...

For this question we must be super careful about identifying the conclusion. The conclusion does NOT say that Kitchen magazine will increase profits by licensing its name to a line of cookware. Also, the conclusion does NOT say that Kitchen magazine will increase its revenue.

The conclusion says "Kitchen can collect its licensing fees without endangering its OTHER revenues"

Let's start by negating answer choice C to get: Makers of cookware WILL find Kitchen a less attractive advertising vehicle because the magazine's name is associated with a competing product.
So by licensing its name to a line of cookware, Kitchen magazine will become a less attractive advertising vehicle.
This negated answer choice, seriously harms the conclusion that "Kitchen can collect its licensing fees without endangering its OTHER revenues"

Now let's negate answer choice E to get: Kitchen is NOT one of the most prestigious cooking-related magazines.
This negated answer choice has no effect on the conclusion that "Kitchen can collect its licensing fees without endangering its OTHER revenues"

Cheers,
Brent

Question link: https://gmatclub.com/forum/the-city-of-workney-in-raising-bus-fares-from...

Hi Kirill. You're correct to say that paying $20 for 18 tokens is equivalent to paying $10 for 9 tokens.
However, the passage suggests that many of Workney's poor people might not have $20 in their pocket at any given time.
So, those poor people would not be able to take advantage of the discounted $20 for 18 tokens.
For this reason, the critics suggested it may be better for the poor people if the city sold 9 tokens for $10.

CONCLUSION: Selling 9 tokens for $10 will alleviate the extra burden on poor people.

When we apply the Negation Strategy to answer choice C we get:
The outlay of $10.00 for the purchase of 9 fare tokens WOULD BE prohibitive for low-income bus riders.

This NEGATED assumption destroys the conclusion that "selling 9 tokens for $10 will alleviate the extra burden on poor people."
If the $10 cost would be prohibitive for low-income bus riders, then the $10 price tag of the discounted tokens would not help poor people at all.

Does that help?

Question link: https://gmatclub.com/forum/infotek-a-computer-manufacturer-in-katrovia-h...

The conclusion: Introducing the new model is unlikely to INCREASE THE NUMBER of computers in Katrovian homes.
There are two ways to increase the number of computers in Katrovian homes:
1) people who don't have a computer buy a computer
2) people who already have a computer buy another computer

Let's examine B and C

(B) The main reason cited by consumers in Katrovia for REPLACING a personal computer is the desire to have an improved model.
There are two problems with this answer choice:

First, we don't know whether Infotek's new computers are better than existing computers, the same as existing computers, or worse than existing computers.
As such, we can't really determine the validity about the choice B.

More importantly, answer choice B involves REPLACING existing computers with Infotek computers. This means the NUMBER of computers in Katrovian homes would not change.

For these reasons, answer choice B is no good.

(C) Katrovians in households that already have computers are unlikely to purchase the new Infotek model as an ADDITIONAL computer for home use.
let's see what happens if we NEGATE answer choice C.
We get: Katrovians in households that already have computers are LIKELY to purchase the new Infotek model as an ADDITIONAL computer for home use.
This negated assumption DESTROYS the conclusion that introducing the new model is unlikely to INCREASE THE NUMBER of computers in Katrovian homes.

As such the correct answer is C

Does that help?

When negating and answer choice, I typically start by adding "IT IS NOT THE CASE THAT" to the beginning of the answer choice. Doing so is typically all you need to understand what the negated answer choices telling us.

That said, here are a few more negations.

SOME means "one or more."
So, the negation of SOME is "none"

The negation is NONE is "some"

The negation of MANY is "not many" (notice that "not many" doesn't really tell us anything)

Cheers, Brent

Question link: https://gmatclub.com/forum/although-the-school-would-receive-financial-b...

Conclusion: Adding soft drink machines to the cafeteria is not in the students' interest
IMPLIED conclusion: Adding soft drink machines to the cafeteria would negatively affect students' health.

(A) If the soft drink vending machines were placed in the cafeteria, students would consume more soft drinks as a result.
If we NEGATE this answer choice, we get: If the soft drink vending machines were placed in the cafeteria, students would NOT consume more soft drinks as a result.
This negated answer choice destroys the conclusion.
So, we'll keep it.

(D) Students will not simply bring soft drinks from home if the soft drink vending machines are not placed in the cafeteria.
If we NEGATE this answer choice, we get: Students WILL bring soft drinks from home if the soft drink vending machines are not placed in the cafeteria.
This tells us that NOT adding soft drink machines to the cafeteria will still negatively affect students' health.
This, however, does not destroy the conclusion, since the conclusion has nothing to do with what happens if soft drink machines are NOT added to the cafeteria.

Does that help?

Question link: https://gmatclub.com/forum/the-technological-conservatism-of-bicycle-man...

Implied conclusion: Since racers are the only ones interested in "better" bicycles, manufacturers should focus solely on innovation that will help racers compete.

(C) Bicycle racers do not generate a strong demand for innovations that fall outside what is officially recognized as standard for purpose of competition.

When we negate this we get: (C) Bicycle racers DO generate a strong demand for innovations that fall outside what is officially recognized as standard for purpose of competition.
This negated premise destroys the argument, since it tells us there's also a demand for innovation that's not related to competition.

As such, C is the best answer.

Question link: https://gmatclub.com/forum/birds-have-been-said-to-be-descended-from-cer...

Argument summary:
It SEEMS like birds descended from bird-like dinosaurs.
However, there are bird fossils that are older than the oldest bird-like dinosaur fossils.
Conclusion: Birds did not descend from bird-like dinosaurs

When we negate answer choice C, we get: There ARE birdlike dinosaur fossils that are older than the bird fossils but have not yet been unearthed.
This negated answer choice exposes a huge assumption in the original argument: just because scientists haven't FOUND bird-like dinosaur fossils that are older than bird fossils, we can't assume that such bird-like dinosaur fossils don't exist.

Here's an analogous argument: Many people believe that the Canadian mint started producing 1-dollar coins BEFORE it started producing 2-dollar coins. The coins in my pocket, however, dispute this, since there are 2-dollar coins in my pocket that are older then the oldest 1-dollar coin in my pocket.

Answer choice C, when negated, destroys the original conclusion by suggesting there ARE bird-like dinosaur fossils that are older than bird fossils.
As such, it's the best answer.

Question link: https://gmatclub.com/forum/birds-have-been-said-to-be-descended-from-cer...

Argument summary:
It SEEMS like birds descended from bird-like dinosaurs.
However, there are bird fossils that are older than the oldest bird-like dinosaur fossils.
Conclusion: Birds did not descend from bird-like dinosaurs

When we negate answer choice C, we get: There ARE birdlike dinosaur fossils that are older than the bird fossils but have not yet been unearthed.
This negated answer choice exposes a huge assumption in the original argument: just because scientists haven't FOUND bird-like dinosaur fossils that are older than bird fossils, we can't assume that such bird-like dinosaur fossils don't exist.

Here's an analogous argument: Many people believe that the Canadian mint started producing 1-dollar coins BEFORE it started producing 2-dollar coins. The coins in my pocket, however, dispute this, since there are 2-dollar coins in my pocket that are older then the oldest 1-dollar coin in my pocket.

Answer choice C, when negated, destroys the original conclusion by suggesting there ARE bird-like dinosaur fossils that are older than bird fossils.
As such, it's the best answer.

Question link: https://gmatclub.com/forum/proposed-new-safety-rules-for-the-beach-city-...

Argument summary: New safety rules will result in 10% fewer daily flights.
The city's budget depends on taxes on tourist spending, and most tourists arrive by plane.
Conclusion: The new safety rules will reduce the revenue generated by the city.

Notice that it's assumed that a 10% reduction in flights will cause a reduction in the number of tourists.

Answer choice E exposes that assumption. It says:
(E) The response to the adoption of the new safety rules would not include an increase in the number of passengers per flight.

If we NEGATE this answer choice we get: The response to the adoption of the new safety rules WOULD INCLUDE an increase in the number of passengers PER FLIGHT.
So, even though there will be fewer flights, it might actually be the case that there will be more tourists (due to the decrease number of passengers per flight)
This kills the conclusion.

Question link: https://gmatclub.com/forum/a-researcher-discovered-that-people-who-have-...

Argument summary:
People with LOW ISA (immune-system activity) have low mental health
People with NORMAL/HIGH ISA have good mental health
Conclusion: The immune system protects against mental illness

Important: Notice that this is a cause and effect argument, and the implied conclusion is a bad immune system CAUSES mental illness.

When we take answer choice D and negate it, we get: (D) Mental illness CAUSES people’s immune-system activity to decrease.
This destroys the implied conclusion by saying the causation works the other way around.
As such, the correct answer is D

Here's my full solution: https://gmatclub.com/forum/the-reason-much-refrigerated-food-spoils-is-t...

Trying to identify possible assumptions is typically hard, whereas the negation technique is easier to perform (even though it's more time-consuming)

Some students have difficulty with assumption questions primarily because they don't accurately identify the conclusion of the argument.
If the conclusion isn't quite right, then it's going to be extra difficult to identify the correct answer.
So, while identifying the conclusion, be sure to ask yourself "What is this argument trying to convince me of?" Take your time with this step, because it's crucial to solving the question.

Also, don't forget that, in order for an answer choice to be correct, the negated version must DESTROY the argument (i.e., the conclusion no longer follows from the premises). So, if the negated version merely injures/dents the argument, that answer choice isn't correct.

I can't think of anything else beyond the tips noted in the video.

Here's my full solution: https://gmatclub.com/forum/in-recent-years-many-cabinetmakers-have-been-...