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04 Sep 2015, 04:14
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25% (medium)

Question Stats:

74% (01:42) correct 26% (01:53) wrong based on 308 sessions

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Any of the following, if introduced into the argument as an additional premise, makes the argument above logically correct EXCEPT:

A) Technetium-99 is more radioactive than Promethium-61.
B) Promethium-61 and Technetium-99 have equal levels of radioactivity.
E) Technetium-99 is more radioactive than Protactinium-234.

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22 Feb 2016, 20:45
1
Harley1980 wrote:

Any of the following, if introduced into the argument as an additional premise, makes the argument above logically correct EXCEPT:

A) Technetium-99 is more radioactive than Promethium-61.
B) Promethium-61 and Technetium-99 have equal levels of radioactivity.
E) Technetium-99 is more radioactive than Protactinium-234.

210>99
61>234
conclusion: 210>234
it will be the case only when:
1. 210=61
2. 210>61
3. 99=61
4. 99>61
5. 99>234
6. 99=234

A - 99>61 - case 4
B - 61=99 - case 3
C - 61=210 - case 1
D - 61>210 - hm..hold.
E - 99>234 -> case 5.

as we see, only D fits.
D tells that 61>210, but it might be 61 - 234 - 210. since we dont know the relationship of 234 and 210 here, we can't give a definite answer.
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04 Sep 2015, 04:34
here we can use mathematical skills

since prome61>pro..234.

option A tech 99>pro,,61. so tech 99>pro 234.
radon 210>tech 99. it is correct.

option B pro 61=tech99. => tech 99>pro 234.

pro 61>prom234. here we cant deduce any referece.

option E tech 99>pro..234.

option D is correct.

.
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13 Aug 2018, 17:22

Official Explanation

OK, for simplicity, I will say R = (Radon-210), T = (Technetium-99), PM = (Promethium-61) and PN = (Protactinium-234).

The argument has the premises

(i) R > T

(ii) PM > PN

and it wants to conclude R > PN.

This is an EXCEPT question. Four of the five responses will, when added to premises (i) & (ii), make the entire argument valid: these four will be incorrect. One of the answers will either contradict the conclusion or leave open uncertainty, and this oddball answer will be the correct answer to this question.

The credited answer is (D), which says PM > R. This means both R & PN are less than PM, but we are left with uncertainty about how R and PN compare to one another. Choice (D) leaves us with uncertainty, so it is correct answer to the EXCEPT question.

Choice (A) says T > PM. That means R > T > PM > PN, which directly implies that R > PN. Choice (A) turns this into a valid argument supporting the conclusion, so it is incorrect.

Choice (B) says T = PM. That means R > T = PM > PN, which directly implies that R > PN. Choice (B) turns this into a valid argument supporting the conclusion, so it is incorrect.

Choice (C) says PM = R. That means R = PM > PN, which directly implies that R > PN. Choice (C) turns this into a valid argument supporting the conclusion, so it is incorrect.

Choice (E) says T > PN. That means R > T > PN, which directly implies that R > PN. Choice (E) turns this into a valid argument supporting the conclusion, so it is incorrect.
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30 Sep 2019, 02:52
Harley1980 wrote:

Any of the following, if introduced into the argument as an additional premise, makes the argument above logically correct EXCEPT:

A) Technetium-99 is more radioactive than Promethium-61.
B) Promethium-61 and Technetium-99 have equal levels of radioactivity.
E) Technetium-99 is more radioactive than Protactinium-234.

Every answer choice except for D clearly supports the argument.
Option D on the other hand leaves scope for doubting the argument.
Hence D
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