GMAT Verbal: Strengthen/Weaken Arguments 3 — Questions and Answers
Question 1: A nutritionist argues that a high-fiber diet prevents heart disease because populations eating more fiber have lower heart disease rates. Which most weakens this?
- High-fiber populations also exercise more and smoke less (Correct answer)
- Fiber is found in many vegetables
- Heart disease has many symptoms
- Some low-fiber populations are also healthy
Correct answer: High-fiber populations also exercise more and smoke less
Confounding lifestyle factors could account for the lower rates, weakening the fiber-specific claim.
Question 2: A firm argues that switching to four-day workweeks increased profits, noting profits rose afterward. Which would most strengthen the argument?
- Costs and revenue were stable, but profits rose only after the switch and stayed high (Correct answer)
- The firm announced the switch publicly
- Employees enjoyed the extra day off
- A rival firm also became profitable
Correct answer: Costs and revenue were stable, but profits rose only after the switch and stayed high
Holding other factors constant and tying the profit rise to the timing of the change supports causation.
Question 3: An advertisement claims its toothpaste is best because 'four out of five dentists recommend it.' Which most weakens this claim?
- The dentists were asked to recommend any toothpaste, and most listed several brands (Correct answer)
- Some dentists prefer mouthwash
- The toothpaste is more expensive than rivals
- The survey was conducted last year
Correct answer: The dentists were asked to recommend any toothpaste, and most listed several brands
If dentists recommended multiple brands, the statistic does not show the product is uniquely or specifically preferred.
Question 4: A researcher concludes a vaccine works because vaccinated people had fewer infections. Which assumption is necessary?
- Vaccinated and unvaccinated people had similar exposure to the disease (Correct answer)
- The vaccine was free
- All participants were adults
- The vaccine had no side effects
Correct answer: Vaccinated and unvaccinated people had similar exposure to the disease
If exposure differed greatly, the lower infection rate might reflect less exposure rather than the vaccine.
Question 5: A city argues that its anti-litter campaign reduced street litter. Which finding most weakens the argument?
- The city doubled the number of trash bins at the same time (Correct answer)
- Residents recalled seeing the campaign posters
- Litter is a problem in many cities
- The campaign won a design award
Correct answer: The city doubled the number of trash bins at the same time
Adding trash bins is an alternative cause that could explain the litter reduction independent of the campaign.
Question 6: An analyst argues that lowering prices will raise total revenue. Which most strengthens this prediction?
- Demand for the product is highly sensitive to price changes (Correct answer)
- The product is well known
- Competitors charge similar prices
- The company has low debt
Correct answer: Demand for the product is highly sensitive to price changes
High price sensitivity means a lower price draws enough extra buyers to increase total revenue.
Question 7: A blog claims that reading before bed improves sleep because people who read before bed sleep better. Which most weakens the claim?
- People who already sleep well are more likely to have time to read before bed (Correct answer)
- Reading is a relaxing activity
- Many books are available digitally
- Some readers prefer mornings
Correct answer: People who already sleep well are more likely to have time to read before bed
Reversed causation—good sleepers choose to read—undermines the claim that reading produces the better sleep.
GMAT Verbal: Strengthen/Weaken Arguments 3
A nutritionist argues that a high-fiber diet prevents heart disease because populations eating more fiber have lower heart disease rates.
Which most weakens this?