ISI 2014 PEA Answer Key

classic Classic list List threaded Threaded
55 messages Options
123
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

ISI 2014 PEA Answer Key

Amit Goyal
Administrator
 1. (d)
 2. (b)
 3. (b)
 4. (c)
 5. (b)
 6. (a)
 7. (a)
 8. (a)
 9. (c)
10. (b)
11. (c)
12. (a)
13. (d)
14. (a)
15. (b)
16. (a)
17. (b)
18. (c)
19. (a)
20. (a)
21. (b)
22. (b)
23. (a)
24. (b)
25. (c)
26. (b)
27. (d)
28. (d)
29. (d)
30. (b)

Ref: MSQE 2014 PEA
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: ISI 2014 PEA Answer Key

aman
Thanks a lot sir..
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: ISI 2014 PEA Answer Key

Shahbaaz Khan
Sir,

Plz clarify this doubt

In ques no 6, the occurrence of 4 on the blue die will effect the result of the Event E as (3,4) is one of the event for event E to take place. Dont you think Event E and F are dependent ??

N sir it would be of great help if you could help in solving ques no 7,10 and 14

Thanks :)
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: ISI 2014 PEA Answer Key

Amit Goyal
Administrator
For Q 5.
Pr(E) = Pr(the sum of the numbers on the two dice is 7) = 1/6
Pr(F) = Pr(the number on the blue die equals 4) = 1/6
Pr(E. F) = Pr(F, G) = 1/36
Since, we also have Pr(E)Pr(F) = 1/36
Therefore, E and F are independent.
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: ISI 2014 PEA Answer Key

Amit Goyal
Administrator
In reply to this post by Shahbaaz Khan
For Q 7, we have to count the number of ways in which we can fill these seven spots using letters from {A, B, C} so that A cannot be followed by B, B cannot be followed by C, and C cannot be followed by A
_ _ _ _ _ _ _
First spot can be filled by any of the three letters, i.e. in three ways. Once the first spot is filled, we have only two ways to fill the second spot. For example, if the first spot is filled by A, then second spot will be taken by either A or C. Similarly for the third spot and so on. So there are 3(2^6) = 192 ways.




Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: ISI 2014 PEA Answer Key

Amit Goyal
Administrator
In reply to this post by Shahbaaz Khan
For Q 10 the easiest way to do it is to recognise that F(x) <= G(x) for all x means that for any x, X takes smaller values less than x is more likely to occur in G than in F. Or in other words, X takes smaller values than x in G more often than it takes in F. So, expectation of X in F must be greater than or equal to expectation of X in G. More formal proof is attached.
sol.png
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: ISI 2014 PEA Answer Key

Amit Goyal
Administrator
In reply to this post by Shahbaaz Khan
For Q 14,
One of the ways to do this problem is:
Pr(Head turns up for the first time after even number of tosses)
= Pr(TH) + Pr(TTTH)+ Pr(TTTTTH) + ......
where TH is the event that first toss is tail and second is head, TTTH is the event that first three tosses are tails and forth toss is heads, etc. Thus,
Pr(Head turns up for the first time after even number of tosses)
= [1/(2^2)] + [1/(2^4)] + [1/(2^6)] + ...
This is a geometric series that sums to 1/3.



Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: ISI 2014 PEA Answer Key

Varun
In reply to this post by Amit Goyal
Amit sir,

Can u plz describe the approach for solving 23rd? can't we solve for real n equal roots of given quadratic equation giving 'alpha'  = 12.25 or none of these as answer?
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: ISI 2014 PEA Answer Key

Amit Goyal
Administrator
This post was updated on .
For Q 23,
You can do the problem directly by observing that (x -1)(x^2 - 7x + a) = 0 has one root as 1. It will have exactly two roots under the following two cases:
(i) (x^2 - 7x + a) = 0  has two distinct roots and one of the roots is 1.
(ii) (x^2 - 7x + a) = 0  has exactly one root that is not equal to 1.

In case (i), for x^2 - 7x + a to be divisible by (x - 1), a must be equal to 6.
Thus, for a = 6
x^2 - 7x + 6 = (x-1)(x-6)
we have two roots.

In case (ii), a = (3.5)^2 = 12.25
Thus, we have option (a) 6
as the right answer.


Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: ISI 2014 PEA Answer Key

Shahbaaz Khan
In reply to this post by Amit Goyal
Thanks a lot sir  :) Really helpful
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: ISI 2014 PEA Answer Key

shraddha.bhatia11
In reply to this post by Amit Goyal
please explain question 11 ans 6.
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: ISI 2014 PEA Answer Key

The Villain
In reply to this post by Amit Goyal
Sir please help me with question 8.Also is there any specific method to solve questions where we are asked to find roots?I really get blown by such questions.Please advice me SIr.
L
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: ISI 2014 PEA Answer Key

L
In reply to this post by Amit Goyal
Please explain Q.26.
For these type of questions, I have no idea how to approach.
hs
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: ISI 2014 PEA Answer Key

hs
In reply to this post by Amit Goyal
sir
doesn't after even no of tosses mean on the 3rd than 5th than 7th .....
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: ISI 2014 PEA Answer Key

SINGHAM
Yes, I also had the same doubt.!
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: ISI 2014 PEA Answer Key

kalyani
In reply to this post by Amit Goyal
Sir, thanks for the answer key. Could you please discuss the solution to Q 25? I feel it is (d) All of the above, as the no of persons who shook hands with odd no of persons could possibly be 19, 1 or 20.
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: ISI 2014 PEA Answer Key

aman
In reply to this post by Amit Goyal
Sir, can you explain q 6, how (p-1)^2 is coming?  Plz explain sir..
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: ISI 2014 PEA Answer Key

sarawagisruti
In reply to this post by Amit Goyal
Sir, can you please solve question 13 and 27?
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: ISI 2014 PEA Answer Key

Arushi
In reply to this post by kalyani
HI kalyani, even I think it should be (d) for Q25, since the question says that "each person shakes hands with some of the persons at the party". Cant understand what we're missing out. :/
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: ISI 2014 PEA Answer Key

Shefali
how to solve quest 9?
123
Loading...