All psychiatrists are doctors. Only psychiatrists were invited to the

Question

Competition Mode Question

All psychiatrists are doctors. Only psychiatrists were invited to the conference. All who were invited to the conference stayed at the Hefford Hotel. Therefore, only psychiatrists stayed at the Hefford Hotel.

Which one of the following statements, if added as a premise to the argument, would make the conclusion valid?

(A) Only those who were invited to the conference stayed at the Hefford Hotel.

(B) All who were invited to the conference were psychiatrists.

(C) All psychiatrists were invited to the conference.

(D) No one who was invited to the conference failed to stay at the Hefford Hotel.

(E) Only doctors stayed at the Hefford Hotel.

jrk23 · Answer

Is "b" is the answer .
E can't be possible because psychiatrist is a subset of doctor

C - no because all psychiatrist are invited mean anyone else can also be invited so not possible

D- provide no information

So I think "b" ...correct me if I am wrong.

Posted from my mobile device

exc4libur · Answer

NOTES: (E) only doctors stayed there, could imply any doctor, not only psychiatrists.

Ans (A)

unraveled · Answer

All psychiatrists are doctors. Only psychiatrists were invited to the conference. All who were invited to the conference stayed at the Hefford Hotel. Therefore, only psychiatrists stayed at the Hefford Hotel.
Which one of the following statements, if added as a premise to the argument, would make the conclusion valid?

(A) Only those who were invited to the conference stayed at the Hefford Hotel. CORRECT. Two ONLY's together completely say that only psychiatrists stayed at the Hefford Hotel - Only psychiatrists were invited and only those who were invited to the conference stayed at the Hefford Hotel'.

(B) All who were invited to the conference were psychiatrists. WRONG. Nothing new here.

(C) All psychiatrists were invited to the conference. WRONG. Let's say there are 100 psychiatrists out of which 50, all of whom were doctors, were invited as per the argument. Now all 100 psychiatrists were invited to conference. Again point to be noted that argument still remains same except that the number of psychiatrists have changed.

(D) No one who was invited to the conference failed to stay at the Hefford Hotel. - WRONG. As B, nothing new here.

(E) Only doctors stayed at the Hefford Hotel. - WRONG. If other doctors stayed in the hotel then this option fails to say that ONLY psychiatrists stayed at hotel.

IMO Answer A.

freedom128 · Answer

psychiatrists --> doctors. 
Only psychiatrists --> conference --> Hefford Hotel
CONCLUSION: only psychiatrists --> Hefford Hotel.

(A) This is CORRECT ANSWER as no one, except all who were invited to the conference (psychiatrists), stayed at the hotel.
(B) just a restatement of the premise
(C) is just an additional information that doesn't help to make the conclusion valid.
(D) is irrelevant and doesn't help to make the conclusion valid. 
(E) is just an additional information that can weaken the conclusion.

FINAL ANSWER IS (A)

shameekv1989 · Answer

All psychiatrists are doctors. Only psychiatrists were invited to the conference. All who were invited to the conference stayed at the Hefford Hotel. Therefore, only psychiatrists stayed at the Hefford Hotel.

Which one of the following statements, if added as a premise to the argument, would make the conclusion valid?

(A) Only those who were invited to the conference stayed at the Hefford Hotel.  - Correct

(B) All who were invited to the conference were psychiatrists.  - This is given - doesn't add anything to the conclusion

(C) All psychiatrists were invited to the conference.  - Even if it were true, there could be other who stayed at H

(D) No one who was invited to the conference failed to stay at the Hefford Hotel.  - Even if this were true i.e. All P stayed at H doesn't mean only P stayed at H. There could be others who stayed apart from those P's

(E) Only doctors stayed at the Hefford Hotel.  - Same as D.

Premise :- P -> D; Only P invited -> All (Only P) invited stayed at H 
Conclusion :- Only P stayed at Hotel

Only P would stay at Hotel would mean only those who were invited i.e P stayed at H - Answer A

adkikani · Answer

Hi  lnm87

I do not think you can CONNECT a premise and conclusion in manner you did in your analysis.
This argument makes a JUMP from premise to conclusion and (A) fills this gap.

All (only P) invited to conference and stayed at H. 
Therefore, only P stayed at H.

Gap: ONLY P were invited to conference.
(A)Only those who were invited to the conference stayed at the Hefford Hotel.
Those: the pronoun refer to those who were invited to conference, the people stayed at H.
Hence, ONLY P stayed at H.

This follows smoothly from premises to conclusion. I guess what you did was more as an INFERENCE rather than 
finding an assumption (recall an assumption can be a VALID strengthener too) or an answer choice that simply validates
my conclusion.

VeritasKarishma  , can you add your two cents?

unraveled · Answer

Thanks adkikani for the tag. Great that you pointed out and that's how we learn. Although I am no good in CR but for this question here's what i did. I agree that its asking to fill the gap and it looks pretty straightforward. The way question stem is structured('if added as a premise to the argument') you are doing that without any force. So, i let the question stem do the work(OR anyone would have to done that) and answer. So, now it looks like this with A: "All psychiatrists are doctors. Only psychiatrists were invited to the conference. Only those who were invited to the conference stayed at the Hefford Hotel . All who were invited to the conference stayed at the Hefford Hotel.". Refer snapshot Psychiatrists are doctors.png Here Case 1 is as per argument where yellow highlighted part is the gap that needs to be filled. Case 2 is what we are trying to achieve. I think the way I wrote my answer is looking problematic. Well this is very question specific approach otherwise generally we do what you said. Let me know your thoughts.

KarishmaB · Answer

This is what the premises mean: Screenshot 2020-03-15 at 14.41.35.png All in blue circle stay in HH Conclusion: Only psychiatrists stayed at HH To say that only psychiatrists stayed at HH, we need to say that no one else stayed at HH. (A) Only those who were invited to the conference stayed at the Hefford Hotel. Correct. All invitees were psychiatrists. If only invitees stayed there, only psychiatrists stayed at HH.

VerbalBot · Answer

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All psychiatrists are doctors. Only psychiatrists were invited to the

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