Probability Question 136

Question: A coin is tossed 10 times. The probability of getting exactly six heads is

[Kerala (Engg.) 2002]

Options:

A) $ \frac{512}{513} $

B) $ \frac{105}{512} $

C) $ \frac{100}{153} $

D) $ {}^{10}C_6 $

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Answer:

Correct Answer: B

Solution:

p = P (getting a head) $ =\frac{1}{2},q=\frac{1}{2}. $

Required probability = P(six successes) $ ={{}^{10}}C_6{{( \frac{1}{2} )}^{6}}{{( \frac{1}{2} )}^{4}} $

$ =\frac{10!}{6!4!}.\frac{1}{2^{10}}=\frac{105}{512} $ .