Logical reasoning PrepTest 145 · Section 2 · Question 10

Incorrect. The argument is just about whether people did or did not switch, not why some did not switch.

Incorrect. The benefits or downsides of the switch are out of scope—it's just about whether the switch was made by some residents.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Argument Evaluation

Stimulus Summary:
A city banned phosphate-based detergents. Some people might have bought them from out of town, but the amount of phosphates at the water treatment plant went down, so others must have switched to non-phosphate detergents.

Answer Anticipation:
The argument notes a phenomenon—phosphate pollution at the water treatment plant went down last year—and attributes a cause of it—some people obeyed the law and switched to a non-phosphate-based detergent.

Whenever an argument concludes a causal explanation for a phenomenon, you should immediately start thinking about alternative causes. Any question that asks about a potential alternative cause will help in evaluating this argument.

Answer Explanation:
This answer hints at an alternative cause of the decrease in phosphate pollution. If the municipality did make changes to their method of water treatment, then that might explain the change in phosphate levels. If they didn't, then a potential alternative cause is ruled out. Either answer would affect the argument and thus help us evaluate it.

Key Takeaway:
Argument Evaluation questions will frequently have answers that ask questions. Different answers should have a different effect on the argument, and all answers should have an effect. When that's the case, you'll know you have the right answer.

Incorrect. The waterways are out of scope of the argument—the noted metric is that the phosphates in the wastewater at the water treatment plant decreased.

Incorrect. Attempts to stop people from bringing in the phosphate-based detergents are out of scope, and the argument is about those who didn't run out of town to buy the phosphate-based detergents, anyway.