SOLUTION: Suppose I have an unfair coin, it lands on heads 75% of the time. If I flip this coin four times, what is the probability that I will get 2 heads? What is the mean for number of he

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Question 1204802: Suppose I have an unfair coin, it lands on heads 75% of the time. If I flip this coin four times, what is the probability that I will get 2 heads? What is the mean for number of heads? Variance? Standard deviation?
Answer by Edwin McCravy(20054) About Me  (Show Source):
You can put this solution on YOUR website!
Binomial probability, with 

n = number of trials = 4 
p = probability of getting a success on 1 trial = 0.75
x = exact number of successes to get the probability of getting out of n trials.  

C%28n%2Cx%29%28p%5Ex%29%281-p%29%5E%28n-x%29
C%284%2C2%29%280.75%5E2%29%281-0.75%29%5E%284-2%29%22%22=%22%220.2109375

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What is the mean for number of heads? Variance? Standard deviation?

Mean = mu%22%22=%22%22n%2Ap
Variance = sigma%5E2%22%22=%22%22n%2Ap%2A%281-p%29
Standard deviation = sigma%22%22=%22%22sqrt%28n%2Ap%2A%281-p%29%29

You can plug in those formula as well as I can. You may have software to do
all this for you if you learn what's what.
 
Edwin