Posted by **John** on Thursday, June 10, 2010 at 6:12pm.

Consider a binomial random variable where the number of trials is 12 and the probability of success on each trial is 0.25. Find the mean and standard deviation of this random variable. I have a mean of 4 and a standard deviation of 2.25 is this correct

- STATISTICS -
**MathGuru**, Thursday, June 10, 2010 at 9:29pm
For this type of problem:

mean = np = (12)(.25) = 3

standard deviation = √npq = √(12)(.25)(.75) = √(2.25) = 1.5

Note: q = 1 - p

- STATISTICS -
**Anonymous**, Friday, November 20, 2015 at 11:31pm
Assume that a procedure yields a binomial distribution with a trial repeated n times. Use the binomial probability formula to find the probability of x successes given the probability p of success on a single trial.

nequals=55, xequals=22, pequals=0.65

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