logo

Ask Questions, Get Answers

 
X
 Search
Want to ask us a question? Click here
Browse Questions
Ad
Home  >>  JEEMAIN and AIPMT  >>  Mathematics  >>  Class12  >>  Probability
0 votes

A fair coin is tossed 100 times. The probability of getting tails on odd number of times is

 

$\begin {array} {1 1} (A)\;\large\frac{1}{2} & \quad (B)\;\large\frac{1}{8} \\ (C)\;\large\frac{3}{8} & \quad (D)\;None\: of \: these \end {array}$

 

Can you answer this question?
 
 

1 Answer

0 votes
Let X denote the number of tails. Then X is a binomial variate with parameters
$ n = 100\: \: \: \: P = \large\frac{1}{2}$
$ \therefore P(x=r)=100C_r \bigg( \large\frac{1}{2} \bigg) ^{100}\: \: \: \: r=0,1,2,.....100$
Required probability = $ P(x=1) +P(x=3)+.....P(x=99)$
$ = \bigg( \large\frac{1}{2} \bigg)^{100} [100C_1+100C_3+.....+100C_{99} ]$
$ \large\frac{1}{2^{100}} [2^{99} ]$
$ \large\frac{1}{2}$
Hence (A)

 

answered Jan 9, 2014 by thanvigandhi_1
 

Related questions

Ask Question
student study plans
x
JEE MAIN, CBSE, NEET Mobile and Tablet App
The ultimate mobile app to help you crack your examinations
Get the Android App
...