Practice Set: Medium
Twenty original questions at medium difficulty. Explicitly untimed: work at your own pace. Check each answer as you go and read the explanation.
The new drug must be safe. It was approved by regulators, and regulators never approve unsafe drugs.
The reasoning is most vulnerable to criticism because it
The argument assumes regulators never err, but that assumption is exactly what a skeptic would question. It begs the question.
A university found that students who attended review sessions scored higher on finals. Administrators credit the sessions.
Which of the following, if true, most strengthens the administrators' claim?
D rules out the self-selection worry in B: even comparing equally strong students, the sessions helped. That is the key alternative killed.
A hotel chain claims its new booking site increased reservations, pointing to a 15 percent rise since launch.
Which of the following, if true, most weakens the claim?
Seasonality explains the rise without the new site. The "since launch" timing is a coincidence.
Lowering the speed limit will save lives, because higher speeds make crashes deadlier.
The argument depends on the assumption that
A lower limit only saves lives if speeds actually fall. If everyone keeps speeding, the deadliness of crashes never changes.
Most of the committee members voted for the proposal. The chair voted against it.
Which of the following must be true?
"Most" means more than half. Even on a three-person committee, most means at least two, and the chair voted no, so at least two others voted yes.
The project will finish on time. All remaining tasks are minor, and the team has two weeks.
Which of the following, if assumed, guarantees the conclusion?
B locks in both the time estimate and the "no surprises" condition. With those guaranteed, on-time completion follows.
Tara: "The new mall will revive downtown because shoppers will come for the stores and stay for the restaurants." Umar: "Shoppers may come, but the mall's chain stores will drive local shops out of business, so downtown will be worse off."
Tara and Umar disagree about whether
Umar grants the foot-traffic point but disputes the net effect. The disagreement is the bottom line for downtown.
Ancient peoples built the pyramids without modern tools, so modern claims that the task is difficult must be wrong.
The reasoning is flawed because it
Doing something with huge labor over decades does not make it easy. The argument ignores the cost in time and workers.
A town replaced its streetlights with LEDs and saw nighttime accidents fall 12 percent. The mayor credits the LEDs.
Which of the following, if true, most strengthens the mayor's claim?
The effect is strongest where the mechanism (better lighting) should matter most. That dose-response pattern is strong causal evidence.
Employees with standing desks take fewer sick days, so standing desks improve health.
Which of the following, if true, most weakens the argument?
A third factor, health consciousness, explains both the desk choice and the sick days. The desks may do nothing.
The candidate promises lower taxes, better schools, and safer streets. But every promise depends on revenue the city does not have. Without money, the platform is a wish list, not a plan.
The main point is that
The final sentence delivers the verdict: the platform cannot work as a plan. The funding gap is the reason.
The economist argued that rent control reduces housing supply, citing three cities where supply fell after controls took effect. But in each city, supply was already falling before the controls. The trend predates the policy.
The argument proceeds by
The speaker accepts the data but reframes it: the fall started before the policy, so the policy cannot be the cause.
All of the paintings sold at the auction were by living artists. "Harbor at Dawn" was sold at the auction.
What must be true?
Direct application of the universal claim to a member of the group. The other choices add unsupported details.
If the alarm had sounded, the guards would have come. The guards did not come. So the alarm did not sound.
Which of the following follows the same pattern?
Both are modus tollens: if P then Q, not Q, therefore not P. A affirms the consequent, a classic error.
The merger will benefit shareholders because the combined company will cut duplicate costs.
The argument assumes that
Cost cuts only help shareholders if they exceed what the merger itself costs. A messy, expensive merger can erase the savings.
A nonprofit claims its tutoring raised math scores, noting that tutored students gained 10 points on average.
Which of the following, if true, most strengthens the claim?
Lottery assignment plus a comparison group is the gold standard. The 8-point gap is now attributable to the tutoring.
A study found that people who eat breakfast live longer, so eating breakfast extends your life.
Which of the following, if true, most weakens the argument?
Breakfast skippers differ in many unhealthy ways. Those habits, not the missing breakfast, may explain the shorter lives.
We should not listen to the senator's tax plan. He has been wrong about every economic prediction he ever made.
The reasoning is vulnerable because it
Even a stopped clock is right twice a day: a bad track record does not prove this plan is bad. Evaluate the plan, not the person.
Each of the team's five starters scored in double figures. No bench player scored in double figures.
Which of the following must be true?
Five starters hit double figures and zero bench players did, so exactly five players did. C is likely but not forced.
The new zoning law is meant to increase affordable housing, but it lets developers pay a fee instead of building units. Every developer will pay the fee. The law will produce fees, not homes.
The main conclusion is that
The final sentence states the predicted outcome. The fee loophole is the mechanism.
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Last updated October 12, 2026