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1)

If getting a head on a coin when it is  tossed is considered as success, then the probability  of having  more number of failures when  ten fair coins are tossed simultaneously , is 


A) 10528

B) 7327

C) 19329

D) 638210

Answer:

Option C

Explanation:

n=10, p=12, q= 12

  Required probability = P(r\geq6)

 =P(r=6)+P(r=7)+P(r=8)+P(r=9)+P(r=10)

=^{10}C_{6}\left(\frac{1}{2}\right)^{10}+^{10}C_{7}\left(\frac{1}{2}\right)^{10}+^{10}C_{8}\left(\frac{1}{2}\right)^{10}+^{10}C_{9}\left(\frac{1}{2}\right)^{10}+\left(\frac{1}{2}\right)^{10}

=\frac{1}{2^{10}}\left(^{10}C_{6}+^{10}C_{7}+^{10}C_{8}+^{10}C_{9}+1\right)

 =\frac{1}{2^{10}}\left(210+120+45+10+1\right)=\frac{386}{2^{10}}=\frac{193}{2^{9}}