#17 - Certain instruments used in veterinary surgery can be

[Administrator]

Complete Question Explanation

Cannot Be True. The correct answer choice is (B)

This is a brutally difficulty #%s problem, and the difficulty is compounded by the Cannot Be True question stem.

The difficulty in this stimulus is found in the numbers and ratios, which can get complicated quite quickly, and in the fact that the information given regards the cleaning of a set of instruments 50 times. The information you are given seems relatively straightforward:

• Nylon set: 50 sterilizations of the set require 3.4 times the energy needed to make the set.
  Stainless set: 50 sterilizations of the set require 2.1 times the energy to make the set.

Note that the ratio is cleaning to manufacturing so we can't be certain about any comparison between the two sets, because each could have wildly different manufacturing numbers. Thus, any answer choice comparing the two will be highly suspect.


Answer choice (A): The stimulus provides no information regarding the actual amounts of energy used—just the ratio between the energy required to manufacture, and the energy required to sterilize. Thus, we cannot compare nylon to steel sterilizations.

Answer choice (B): This is the correct answer choice. The key here is to realize that the answer choice refers to "each" single complete sterilization of each nylon set and not all 50 sterilizations. So, because we know that cleaning 50 sets (or one set, 50 times), requires 3.4 times the energy needed to manufacture one set, that means that with the energy we need to manufacture one set, we do about 14 sterilizations (50/3.4). Let's make up a numerical example to help show what's happening:

• Nylon set manufacturing energy = 100 units
  Nylon set, 50 sterilizations = 340 units (for ALL 50)
  
  Nylon set, 1 sterilization = 340/50 units = 6.8

Therefore, there is no way that the energy to manufacture one set (100 in our example above) would be less than the energy to sterilize one set (6.8 in our example above).

Answer choice (C): Again, since the stimulus provides no information regarding actual numbers (just proportions), there is no way to compare the two sets. This could be true, so this answer choice cannot be correct.

Answer choice (D): Like the other answers that compare the energy used in nylon vs steel, there is no way to assess whether or not this was the case, so it could be true.

Answer choice (E): The author never made a cost comparison, so this could also be true, based on limited information provided.

[milanproda@me.com]

Prep Test 9 Section 2 Question 17

This question seems to be a Must Be True X type question:

If the statements above are true, each of the following could be true EXCEPT:

The question is difficult (to me) because the wording seems very vague.



Answer A: Could be true. The Amount of energy used is relative (no hard data is given). The amount of energy used for nylon sterilizations can be 1,000,000, watts while the steel can be 3.4 watts.

B-Correct answer. I am not sure what the test makers mean by "more energy was required for EACH complete sterilization". How can this NOT be true?

C-Again, the data is not concrete. We were not given an exact amount of instruments, so this could be true.

D-Same as A&C

E- Cost is not mentioned, and since this is a must be true X, we can eliminate the answer.

I was hoping to get an explanation on the logic of question.

Thank you ahead of time.

[Steve Stein]

That's an interesting question, with a bit of math involved. Whatever amount of energy it took to make the set of nylon instruments, it only took a bit more than triple that amount to do 50 sterilizations! That means that the creation of a set must take roughly as much energy as 15 complete cleanings.

For example, lets say it takes 100 watts of energy to make a set of instruments:
100 watts = 1 set created

Then it would take 340 watts to do 50 compete sterilizations:
340 watts = 50 sterilizations
340/50 watts = 1 sterilization
6.8 watts = 1 sterilization

No matter how much energy is actually used, there is no way that one sterilization can take more enerty than the creation of one set of instruments.

Tough one--let me know whether it's clear--thanks!

~Steve

[reop6780]

The correct answer is B.

I thought answer B "must be true" instead of "cannot be true."

I must be missing something.

The stimuli states that starilization of nylon sets required 3.4 times manufacturing nylon set.

Based upon this fact, B seems to be "must be true."

What am I missing in this question?

Thank you, powerscore !

[Robert Carroll]

reop,

The stimulus says that 50 sterilizations takes 3.4 times the energy of manufacturing. A single sterilization will be 50 times smaller than that. So it will be much, much smaller than the energy of manufacturing the set.

Robert Carroll

[kristinaroz93]

"Certain instruments used in veterinary surgery.."

This is a very confusing problem. I don't quite understand the math/logic/intuition behind it at all. Would anyone mind explaining why each choice is wrong and B is right using mathematical terms?


Thanks in advance!

-Kristina

[Steve Stein]

Hey Kristina,

That's a great question, and one that many students find quite challenging, but it may become easier if we make it a bit more concrete. The author provides that 50 sterilizations of a nylon set require 3.4 times as much energy as it takes to make the set. So, if, for example, it costs $100 worth of electricity to produce a nylon set, then it would cost 3.4 times that, or $340, to do 50 sterilizations of that set—meaning that each individual sterilization would cost $6.80.

The question asks for the answer choice that cannot be true. Answer choice (B) claims that each individual sterilization of that nylon set cost more than it cost to produce the set. But as we can see from the discussion above, if it cost $100 to produce the set, then each individual sterilization would only cost $6.80. As such, it is cannot be the case that each $6.80 sterilization cost more than the $100 cost to produce the set.

Since that is the only answer choice that cannot possibly be accurate, it is the right answer in this case. I hope that's helpful! Please let me know whether this clear, and whether any of the other answer choices still seem appealing—thanks!

~Steve

[kristinaroz93]

Dear Steve,

I completely understand this problem now! Thanks so much for all your help =)

Best,

Kristina

[Nicholas Noyes]

Hello,

Can I please get an explanation as to why answer B is the correct answer? I am confused to what the wording of answer B is actually describing and how it cannot be true.

I am taking a guess here but in the stimulus, it says that 50 sterilizations for nylon instruments takes 3.4 times the amount of energy required to manufacture them. So that would mean that to sterilize the nylon set of instruments one time we would divide 3.4/50 = 0.068. So to sterilize the nylon instruments one time it would take 0.068 times the amount of energy it took to produce the set....And this is why ANSWER B cannot be true, because in this answer choice it says "More energy was required for EACH complete sterilization" (not the total 50 sterilizations) and we know by doing the math that it does not take more energy for a single (each) sterilization.

Please let me know if my thought process is correct here or if I am on the right track. I could see that this was a difficult question that other students struggled with.

Thank You,
Nicholas

[tug59567]

I am also struggling to understand this question. Why is answer choice C incorrect? I was reluctant to pick it but the stimulus is very clear that 50 needles of each were tested. I immediately disregarded answer choice B (correct answer) because it should be true. The stimulus says to sterilize the nylon instruments "required 3.4 times the amount of energy used to manufacture that set of instruments". This leads me to believe that the act of sterilization requires more energy than the act of manufacturing.

I think the word that is causing me to disagree in answer choice B is "each". I assumed that referred to 1 complete sterilization of all 50 needles - assuming the needles are sterilized in a batch, although the stimulus doesn't specify.

Any general explanation for this question would be greatly appreciated.

Thanks