CCTST Inference 2 — Questions and Answers
Question 1: A study finds that cities with more coffee shops per capita have higher average incomes. What can most reasonably be inferred?
- Coffee shops cause higher incomes.
- Higher incomes and coffee shop density are correlated but causation is unproven. (Correct answer)
- People in wealthy cities drink more coffee than others.
- Coffee shops should be built to raise city incomes.
Correct answer: Higher incomes and coffee shop density are correlated but causation is unproven.
Correlation between two variables does not establish which causes which or whether a third factor explains both.
Question 2: All mammals are warm-blooded. Whales are mammals. Which inference is best supported?
- Whales live in warm water.
- Whales are warm-blooded. (Correct answer)
- All warm-blooded animals are mammals.
- Whales evolved from land mammals.
Correct answer: Whales are warm-blooded.
Applying the universal property of mammals to whales, a member of that class, is a valid deductive inference.
Question 3: Maria leaves home at 8:00 AM and arrives at work at 8:45 AM. The next day she leaves at 8:15 AM and encounters no traffic delays. What can be inferred about her arrival time?
- She will arrive exactly at 9:00 AM.
- She will likely arrive around 9:00 AM if travel time is consistent. (Correct answer)
- She will be late because she left later.
- Traffic delays always affect commute time.
Correct answer: She will likely arrive around 9:00 AM if travel time is consistent.
If travel conditions are similar and the trip took 45 minutes before, leaving 15 minutes later suggests arriving around 9:00 AM.
Question 4: A patient's blood pressure drops after starting a new medication. The doctor infers the medication is working. Which additional fact would most strengthen this inference?
- The patient also changed their diet.
- No other variables changed during the same period. (Correct answer)
- Blood pressure naturally fluctuates day to day.
- The medication is widely advertised.
Correct answer: No other variables changed during the same period.
Ruling out confounding variables strengthens the inference that the medication caused the blood pressure drop.
Question 5: The statement 'Some athletes are vegetarians' best supports which inference?
- All athletes are vegetarians.
- No athletes eat meat.
- At least one athlete follows a vegetarian diet. (Correct answer)
- Vegetarian diets improve athletic performance.
Correct answer: At least one athlete follows a vegetarian diet.
'Some' means at least one, so it is valid to infer that at least one athlete is a vegetarian.
Question 6: A graph shows ice cream sales and drowning rates both rise in summer. What is the most cautious inference?
- Ice cream consumption causes drowning.
- Drowning causes people to crave ice cream.
- A third factor, such as hot weather, likely drives both trends. (Correct answer)
- The data are too unreliable to analyze.
Correct answer: A third factor, such as hot weather, likely drives both trends.
When two variables move together due to a shared cause, the correlation is spurious and no direct causal link should be inferred.
Question 7: If it is true that 'No birds are reptiles' and 'All penguins are birds,' what can be inferred?
- Some penguins are reptiles.
- No penguins are reptiles. (Correct answer)
- All reptiles are birds.
- Penguins and reptiles share a common ancestor.
Correct answer: No penguins are reptiles.
Because penguins belong to birds, and no birds are reptiles, it follows necessarily that no penguins are reptiles.
CCTST Inference 2
A study finds that cities with more coffee shops per capita have higher average incomes.
What can most reasonably be inferred?