# ISI Sample Paper PEA 2016 Discussion Classic List Threaded 32 messages 12
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## ISI Sample Paper PEA 2016 Discussion

 This post was updated on .    I found these choices to be true. Please let me know if mistakes are present. Updated with Sir's answer key. 1. c 2. b 3. d 4. a 5. c 6. d 7. d 8. b 9. a 10. a 11. d 12. b 13. a 14. Question not correct 15. c 16. d 17. c 18. b 19. c 20. c 21. d 22. a 23. b 24. a 25. c 26. d 27. a 28. a 29. a 30. c
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## Re: ISI Sample Paper PEA 2016 Discussion

 how di u got q. 16 answer as d) plzz explain
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## Re: ISI Sample Paper PEA 2016 Discussion

 In reply to this post by Dr. Strange Question 2 Why is it sufficient?
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## Re: ISI Sample Paper PEA 2016 Discussion

 In reply to this post by Dr. Strange can u plz tell how to do ques no.29
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## Re: ISI Sample Paper PEA 2016 Discussion

 @varnika take f(x,y) = x^2-y^2 and solve
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## Re: ISI Sample Paper PEA 2016 Discussion

 This post was updated on . In reply to this post by varnika1880 Open this post in threaded view
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## Re: ISI Sample Paper PEA 2016 Discussion

 thnx but my query is in the second eq of the question x,y{r2) . but the fn goes from r2to r1..won't this fact be considered while solving
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## Re: ISI Sample Paper PEA 2016 Discussion

 In reply to this post by samuraijack Are you implying this because of the equality sign present? Since it is mentioned that function is twice differentiable I have doubt whether this means higher derivatives don't exist or are equal to 0. In second case second derivative must be nonzero where first derivative is 0 and it will be necessary and sufficient condition.However if third or higher derivatives exist then it will only be a necessary condition as the point can be inflection point. My doubt lies on meaning of twice differentiable.
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## Re: ISI Sample Paper PEA 2016 Discussion

 Yes, I think twice differentiable can be there to distinguish it from a straight line y=c; so we should consider inflection points too.
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## Re: ISI Sample Paper PEA 2016 Discussion

 So what is your opinion: can we call y=x^3 a twice as well as a thrice differentiable function or shall we call it only a thrice differentiable function?
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## Re: ISI Sample Paper PEA 2016 Discussion

 x^3 is both twice and thrice differentiable, we're only given it's a twice differentiable fuction nothing about possibilities of higher order derivatives, it may or may not exist. But again I am not sure.
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## Re: ISI Sample Paper PEA 2016 Discussion

 However I think you are right. Since it is not mentioned about higher derivatives I can't take it for granted. Changing my option  and making it only a necessary condition.
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## Re: ISI Sample Paper PEA 2016 Discussion

 In reply to this post by Dr. Strange @Dr Strange Can you explain Q13,14,21,26.
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## Re: ISI Sample Paper PEA 2016 Discussion

 13.System is homogenous.So either trivial soln(0,0,0,)exists or infinite soln exists. So for non-zero soln to exist determinant should be 0. Making determinant zero we get the soln. 21.four cases are possible: (red,not red),(red,red),(not red,red),(not red,not red) P(red,red)=a/n* (a-1)/(n-1) P(not red,red)=(n-a)/n * a/(n-1) p(second ball is red)=P(red,red)+P(not red,red)= a/n 26.given constraint x=y put x=y in target equation and optimise
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## Re: ISI Sample Paper PEA 2016 Discussion

 14.Since cumulative distribution function attains value 1 at x=infinity so it is only possible if a=0 and b=1     F(x)= 1 for x>=0           =x^2-x +1 for x<0   Since x is defined for [0,1] so second part becomes redundant. so the distribution is discrete having p(x)=1 at x=0 and p(x)=0 elsewhere problem is  question mentions that 'a' belongs to (0,1) so a=0 is not a viable solution.I am stuck in here. If ' a ' is considered to be 0 then F becomes continuous in (0,1).
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## Re: ISI Sample Paper PEA 2016 Discussion

 In reply to this post by Dr. Strange I read it in a book which says it's both a sufficient and necessary condition
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## Re: ISI Sample Paper PEA 2016 Discussion

 In reply to this post by Dr. Strange Can u please tell how u r getting d as an ans for 21
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## Re: ISI Sample Paper PEA 2016 Discussion

 I have displayed the solution of 21 in above post.
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## Re: ISI Sample Paper PEA 2016 Discussion

 In reply to this post by Dr. Strange If we sum up the two value over two intervals and equate it to one ...and then in that eq replacing X by a ...we will get a=1 but 1 Doesn't belong to the given interval...so it might be the case that it's not continuous at a