(A) points to a different common flaw that doesn’t happen here – the value judgment. It is indeed inappropriate to infer normative conclusions (about how things ought to be) from merely descriptive premises (about how things are).

The stimulus never uses normative language, though. All its claims are descriptive.

Applying (B) to the stimulus, there needs to be a property that does apply to people on average, which the stimulus then tries to apply to every individual person. Like “iguanas are 12in long on average, so all the zoo’s iguanas must be 12in long.”

The stimulus never makes a jump between statistical figures and individual applications. All its claims, including the conclusion, are about what we can expect “on average.”

If you’re familiar with LSAT math questions, (C) fits the mold well enough that you don’t even need to spend time noodling out hypothetical situations. “What if the sample sizes are super different?” is the archetype for solving percent vs. amount puzzles.

The hypothetical we discuss in the analysis section – which features a very low proportion of cokeheads in the population – serves as a counterexample to the argument’s conclusion. It’s a scenario in which the majority of people who tested positive were not cokeheads.

Change the proportion of cokeheads to sobers, though, and you get a different situation. If there are equal numbers of cokeheads and sobers walking around, a random sample would yield more positive-cokeheads than positive-sobers.

Far from ignoring it, the argument establishes this fact explicitly.

(E) points to a different common flaw that doesn’t happen here – the value judgment. It is indeed inappropriate to infer normative conclusions (about how things ought to be) from merely descriptive premises (about how things are).

The stimulus never uses normative language, though – it never advocates anything. All its claims are descriptive.