Bunuel
The main ingredient in this bottle of Dr. John’s Milk of Magnesia is used by nine out of ten hospitals across the country as an antacid and laxative.
If this advertising claim is true, which of the following statements must also be true?
(A) Nine out of ten hospitals across the country use Dr. John’s Milk of Magnesia for some ailments.
(B) Only one out of ten hospitals in the country does not treat acid indigestion and constipation.
(C) Only one out of ten hospitals across the country does not recommend Dr. John’s Milk of Magnesia for patients who need a milk of magnesia.
(D) Only one of ten hospitals across the country uses a patent medicine other than Dr. John’s Milk of Magnesia as an antacid and laxative.
(E) Nine out of ten hospitals across the country use the main ingredient in Dr. John’s Milk of Magnesia as an antacid and laxative.
"Must be true" --> inference question. So, we don't need conclusion and premise(s). Let's look at the answer choices:
(A) Nine out of ten hospitals across the country use Dr. John’s Milk of Magnesia for some ailments.
We are told that nine out of ten hospitals use the MAIN INGREDIENT in Dr. John's, not that they necessarily use Dr. John's. Eliminate.(B) Only one out of ten hospitals in the country does not treat acid indigestion and constipation.
The remaining hospitals could use something else to treat these issues. Eliminate.(C) Only one out of ten hospitals across the country does not recommend Dr. John’s Milk of Magnesia for patients who need a milk of magnesia.
We have no idea how many hospitals do or don't recommend Dr. John's. Maybe zero hospitals recommend this specific brand. All we know is that nine out of ten use the INGREDIENT in Dr. John's. Eliminate.(D) Only one of ten hospitals across the country uses a patent medicine other than Dr. John’s Milk of Magnesia as an antacid and laxative.
This one is wrong for two reasons. First, just because nine out of ten people drink coffee doesn't mean that nine out of ten people don't also drink tea. Second, it could very well be the case that all of the "nine out of ten" use a patent medicine other than Dr. John's; remember that we only know that nine out of ten use the MAIN INGREDIENT, and maybe all those use some brand name other than Dr. John's. Eliminate.(E) Nine out of ten hospitals across the country use the main ingredient in Dr. John’s Milk of Magnesia as an antacid and laxative.
That's exactly what we were told. Keep it.Answer choice E.