A pack of 2n cards, n of which are red, and another n are black. It is divided into two equal parts and a...












0












$begingroup$


A pack of 2n cards, n of which are red, and another n are black. It is divided into two equal parts and a card is drawn from each part. Find the probability that the cards drawn are of the same colour.



This is what I have done:
(https://i.stack.imgur.com/kEPOJ.jpg)



And this is what the book has done:
(https://i.stack.imgur.com/CTUjR.jpg)



Please say me who is correct.
( I am unable to do formatting in text as I don't have a net connection on PC)










share|cite|improve this question









$endgroup$












  • $begingroup$
    Both are the same!
    $endgroup$
    – Phicar
    Jan 23 at 6:38










  • $begingroup$
    Please can you explain how?
    $endgroup$
    – Abhishek Ghosh
    Jan 23 at 6:40










  • $begingroup$
    Well the only different thing is the index in the sum, but for the cases $k=0,k=n$ the argument of the sum is 0. You both got $$sum _{k=0}^n2frac{k(n-k)}{n^2}$$
    $endgroup$
    – Phicar
    Jan 23 at 6:44










  • $begingroup$
    Thanks for helping me👍
    $endgroup$
    – Abhishek Ghosh
    Jan 23 at 6:47
















0












$begingroup$


A pack of 2n cards, n of which are red, and another n are black. It is divided into two equal parts and a card is drawn from each part. Find the probability that the cards drawn are of the same colour.



This is what I have done:
(https://i.stack.imgur.com/kEPOJ.jpg)



And this is what the book has done:
(https://i.stack.imgur.com/CTUjR.jpg)



Please say me who is correct.
( I am unable to do formatting in text as I don't have a net connection on PC)










share|cite|improve this question









$endgroup$












  • $begingroup$
    Both are the same!
    $endgroup$
    – Phicar
    Jan 23 at 6:38










  • $begingroup$
    Please can you explain how?
    $endgroup$
    – Abhishek Ghosh
    Jan 23 at 6:40










  • $begingroup$
    Well the only different thing is the index in the sum, but for the cases $k=0,k=n$ the argument of the sum is 0. You both got $$sum _{k=0}^n2frac{k(n-k)}{n^2}$$
    $endgroup$
    – Phicar
    Jan 23 at 6:44










  • $begingroup$
    Thanks for helping me👍
    $endgroup$
    – Abhishek Ghosh
    Jan 23 at 6:47














0












0








0





$begingroup$


A pack of 2n cards, n of which are red, and another n are black. It is divided into two equal parts and a card is drawn from each part. Find the probability that the cards drawn are of the same colour.



This is what I have done:
(https://i.stack.imgur.com/kEPOJ.jpg)



And this is what the book has done:
(https://i.stack.imgur.com/CTUjR.jpg)



Please say me who is correct.
( I am unable to do formatting in text as I don't have a net connection on PC)










share|cite|improve this question









$endgroup$




A pack of 2n cards, n of which are red, and another n are black. It is divided into two equal parts and a card is drawn from each part. Find the probability that the cards drawn are of the same colour.



This is what I have done:
(https://i.stack.imgur.com/kEPOJ.jpg)



And this is what the book has done:
(https://i.stack.imgur.com/CTUjR.jpg)



Please say me who is correct.
( I am unable to do formatting in text as I don't have a net connection on PC)







probability






share|cite|improve this question













share|cite|improve this question











share|cite|improve this question




share|cite|improve this question










asked Jan 23 at 5:48









Abhishek GhoshAbhishek Ghosh

658




658












  • $begingroup$
    Both are the same!
    $endgroup$
    – Phicar
    Jan 23 at 6:38










  • $begingroup$
    Please can you explain how?
    $endgroup$
    – Abhishek Ghosh
    Jan 23 at 6:40










  • $begingroup$
    Well the only different thing is the index in the sum, but for the cases $k=0,k=n$ the argument of the sum is 0. You both got $$sum _{k=0}^n2frac{k(n-k)}{n^2}$$
    $endgroup$
    – Phicar
    Jan 23 at 6:44










  • $begingroup$
    Thanks for helping me👍
    $endgroup$
    – Abhishek Ghosh
    Jan 23 at 6:47


















  • $begingroup$
    Both are the same!
    $endgroup$
    – Phicar
    Jan 23 at 6:38










  • $begingroup$
    Please can you explain how?
    $endgroup$
    – Abhishek Ghosh
    Jan 23 at 6:40










  • $begingroup$
    Well the only different thing is the index in the sum, but for the cases $k=0,k=n$ the argument of the sum is 0. You both got $$sum _{k=0}^n2frac{k(n-k)}{n^2}$$
    $endgroup$
    – Phicar
    Jan 23 at 6:44










  • $begingroup$
    Thanks for helping me👍
    $endgroup$
    – Abhishek Ghosh
    Jan 23 at 6:47
















$begingroup$
Both are the same!
$endgroup$
– Phicar
Jan 23 at 6:38




$begingroup$
Both are the same!
$endgroup$
– Phicar
Jan 23 at 6:38












$begingroup$
Please can you explain how?
$endgroup$
– Abhishek Ghosh
Jan 23 at 6:40




$begingroup$
Please can you explain how?
$endgroup$
– Abhishek Ghosh
Jan 23 at 6:40












$begingroup$
Well the only different thing is the index in the sum, but for the cases $k=0,k=n$ the argument of the sum is 0. You both got $$sum _{k=0}^n2frac{k(n-k)}{n^2}$$
$endgroup$
– Phicar
Jan 23 at 6:44




$begingroup$
Well the only different thing is the index in the sum, but for the cases $k=0,k=n$ the argument of the sum is 0. You both got $$sum _{k=0}^n2frac{k(n-k)}{n^2}$$
$endgroup$
– Phicar
Jan 23 at 6:44












$begingroup$
Thanks for helping me👍
$endgroup$
– Abhishek Ghosh
Jan 23 at 6:47




$begingroup$
Thanks for helping me👍
$endgroup$
– Abhishek Ghosh
Jan 23 at 6:47










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