LSAT 130 | Section 1 | Logical Reasoning: Q20

LR Question 20 Explanation

QUESTION TEXT: A person with a type B lipid profile is at much greater risk

QUESTION TYPE: Must be True

FACTS: Type B lipid profiles have a much higher risk of heart disease.

A low fat diet causes type B profiles to have much lower cholesterol levels, however their lipid profiles didn’t change. (The cholesterol drop is perhaps presumed to be a benefit, based on the “however….no benefit” describing type A)

Type A volunteers got no benefit from the diet, and 40% shifted to type B lipid profiles.

ANALYSIS: Frankly, this stimulus is confusing. Trying to tie everything together is fruitless. It’s best to look at individual parts, and see what you can be sure about. I noticed these parts:

Type B lipid profiles have a greater risk of heart disease. (Since this is a “must be true” question, we know this statement is true.)

40% of type A volunteers shifted to a type B profile.

Combining those, we can say that 40% of the type A volunteers were harmed by the diet, in terms of heart disease risk.

I couldn’t conclude anything else definite. I don’t know what a low fat diet is supposed to do, and I don’t know what the effect of lower cholesterol is supposed to be. Maybe I’m supposed to assume both of those things are good, but the argument doesn’t say so.

___________

1. We don’t know this. Especially since 40% of type A volunteers shifted to a higher risk lipid profile. If there were more type A volunteers, then it’s probable that most people actually had a higher risk of heart disease as a result of the diet.
2. We don’t know: the author never mentioned relative cholesterol levels between the groups. Cholesterol may not be the only factor affecting heart disease risk.
3. The argument doesn’t mention lifestyle factors, so we have no idea.
4. This is entirely unsupported. The type B volunteers didn’t have a change in their lipid profile. And the stimulus didn’t say whether the type A volunteers had a change in their cholesterol levels.
5. CORRECT. This is true of the type A volunteers. After following the diet, 40% of them switched to type B lipid profiles. And the first sentence says that type B profiles have a higher risk of heart disease.