retagged by
5,983 views
14 votes
14 votes
For a given biased coin, the probability that the outcome of a toss is a head is $0.4$. This coin is tossed $1,000$ times. Let $X$ denote the random variable whose value is the number of times that head appeared in these $1,000$ tosses. The standard deviation of $X$ (rounded to $2$ decimal place) is _________
retagged by

1 Answer

Best answer
20 votes
20 votes
It is Independent trails with same rate of success. So we can use Binomial distribution

Probability of success $(p) = 0.4$

Probability of failure $(q) = 1 – 0.4 = 0.6$

Number of trials $(n) = 1000$

Variance $=n\times p\times q = 1000 * 0.4 * 0.6 = 240$

Standard deviation $=\sqrt{240} = 15.49$
edited by
Answer:

Related questions

36 votes
36 votes
4 answers
3