SOLUTION: Let X represent the difference between the number of heads and the number of tails when a coin is tossed 41 times. Then P(X=11)=

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Question 1188499: Let X represent the difference between the number of heads and the number of tails when a coin is tossed 41 times. Then P(X=11)=
Answer by ikleyn(52803)   (Show Source): You can put this solution on YOUR website!
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Let X represent the difference between the number of heads and the number of tails
when a coin is tossed 41 times. Then P(X=11)=
~~~~~~~~~~~~~~~~


It is very nice,  slightly tangled probability problem.
I solved it  (a  TWIN  version)  once at this forum;  see my lesson
    - Challenging problems on Binomial distribution probability
(Problem 1)  in this site.  So,  it is the second time I meet this problem at the forum . . . 


Let H be the number of heads and T be the number of tails.

Then we have these two equations

    H + T = 41

    H - T = 11


We solve this system elementary, using elimination method, and we get H =  = 26;  T = 15.


Now the problem is: find the probability to get 26 heads tossing a coin 41 times.


The answer is  P =  =  = 0.028845659 = 0.02885 (rounded).

Solved.



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