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Aditi Aggarwal

Aditi Aggarwal (Querist)
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07 June 2014 If 10 coins are tossed 100 times, how many times would you expect 7 coins to fall head upward

Nikhil Kaushik

Nikhil Kaushik (Expert)
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07 June 2014 This is the binomial distribution (p+q)^10 with p =1/2, q = 1/2.

You can have 10 heads, probability of this is p^10 or 1/1024

9 heads 1 tail has pr = 10.p.q^9 = 10/1024

8 heads 2 tails has pr = 10C2.p^2.q^8 = 45/1024

7 heads 3 tails has pr = 10C3.p^7.q^3 = 120/1024

So in 100 trials of this you would expect 7 heads & 3 tails to occur 100 x 120/1024 times
or about 11.7 times. Nearly 12 times.

https://in.answers.yahoo.com/question/index?qid=20120616062754AAwJkxQ

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