PrepTest 134, Section 1, Question 9
If a child is to develop healthy bones,(26 more words not shown)
Flawed reasoning in which one(13 more words not shown)
- AIf bread is(32 more words not shown)
- BA cake must(29 more words not shown)
- CThe Bake-a-Thon, which(37 more words not shown)
- DBoth yeast and(26 more words not shown)
- EIn recipe contests,(37 more words not shown)
Reading the argument
A child needs enough calcium to develop healthy bones. But what if the child gets enough calcium and is missing something else?
Maybe another nutrient is needed too. The passage doesn't tell us that calcium is the only requirement. So unhealthy bones could reflect a different problem even when the child's diet contains plenty of calcium. The author notices that the desired outcome failed and immediately blames one particular requirement.
What we’re looking for
That's the mistake we need to match: “You need X to achieve Y. You didn't achieve Y, so you must not have had X.” The first statement only tells us that lacking X rules out success. It doesn't tell us that having X guarantees success or that every failure must be X's fault. Look for another argument that singles out one required ingredient as the explanation for a failed result.
Working the answers
- A
Right temperature corresponds to sufficient calcium, and firm crust corresponds to healthy bones. But the conclusion follows the rule properly: if the bread lacks the required temperature, it cannot have the desired crust. That's like saying a child without enough calcium cannot develop healthy bones.
To make our mistake, A would need to say that bread without a firm crust must have been baked at the wrong temperature. Perhaps some other ingredient was missing. The actual answer doesn't make that unsupported move, so its reasoning is valid rather than parallel to our flaw.
- BCorrect
The right amount of flour plays calcium's role: it is required for the desired result. Tasting good plays the role of healthy bones. Then the argument says a cake that tastes bad must lack the right amount of flour.
Why blame the flour? Perhaps the cake had enough flour but not enough sugar, or it was baked badly. Just as a child might get enough calcium and still have unhealthy bones, a cake might meet this one requirement and still taste bad. B makes the same unsupported diagnosis of failure.
- C
This predicts a future winner's age from the ages of past winners. It doesn't establish an ingredient required for success and then infer its absence from a failed outcome. A historical pattern is doing the work, not a requirement like calcium or flour.
- D
Yeast and baking powder are two things that can help rolls rise. The conclusion treats them as freely interchangeable. That's a claim about substituting one ingredient for another, not an inference that an unsuccessful result proves the absence of a required ingredient.
- E
This compares the numbers entering two contest categories and draws a conclusion about contestants' chances. There is no stated requirement for winning followed by a claim that losing proves the requirement was absent. The recipe topic resembles B's topic, but the structure is different.
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