#17 - To measure a small boat hull accurately, it is necessary to level the hull

[Administrator]

Complete Question Explanation

Must Be True. The correct answer choice is (D).

Answer choice (A):

Answer choice (B):

Answer choice (C):

Answer choice (D): This is the correct answer choice.

Answer choice (E):

This explanation is still in progress. Please post any questions below!

[zoezoe6021]

According to the stimulus,

Accurately measure→Level the hull→"line level"

(D) is correct because it says Accurately measure→"line level"

But I don't understand why (B) is incorrect.

I see "provided that" as "only if" , so I think (B) states that Accurately measure→Level the hull

[Jeff Wren]

Hi Zoe,

Your diagram of the stimulus looks good, as does your description of Answer D.

Unfortunately, your interpretation of Answer B is backwards.

Here, "provided that" would be equivalent to "if" rather than "only if" and would introduce the sufficient condition.

What Answer B is basically saying is:

If (i.e. provided that, given that, etc.) they have leveled the hull, then they accurately determined the hull’s dimensions.

This is a Mistaken Reversal of what is stated in the stimulus.

[ar0438]

Answer B states: "The scientists accurately determined the hull's dimensions, provided that they leveled the hull."

This is too strong, it basically says that as long as the "Leveled Hull" step was completed, they were able to accurately determine the dimensions. But what if other mistakes were made in the actual measuring stage. We cannot know for sure that no other mistakes were made, specially since the prompt specifies that the scientist did not have "any experience measuring hulls". So it is totally possible that other mistakes would be made that would prevent them from getting accurate results.

Now lets looks at answer D

"The scientists were able to accurately record the hull's dimensions only if they used a line level."

This just shows that as long as they use a line level, they are "able" to get the right measurements. It doesn't guarantee that they will, only that they are "able" to get them, which is true, you do need that specific tool to even have a possibility of having the right measurents in the end.

[lounalola]

So is answer B a mistaken reversal?

[Adam Tyson]

Yes, as Jeff explained earlier in this thread, answer B is a Mistaken Reversal.