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SusanZ
11-13-2005, 06:31 PM
Wish I'd found your site a long time ago!
I have been working on this all day long with no success and I don't know what to do.

I am to constuct a binomial probability distribution with the given parameters of n=6, p=0.3

I think my sample size is x=0,1,2,3,4,5,6......but how do I figure the rest of it? I have the answers (from the back of the book), but nothing I've done thus far has even been close.

If I can get help on this part, I will be able to move on to the other portions of the question..i.e., compute the mean and standard deviation of the distribution (using 2 different methods), and draw the probability histogram

Please give me some guidance with this if you can. Thank you, Susan

JohnM
11-13-2005, 10:10 PM
SusanZ,

What does p = 0.3 represent --> what event? You'll need that to draw the histogram.

The mean of a binomial is n*p
the standard deviation is the square root of (n*p*q) where q = 1-p

JohnM

JohnM
11-15-2005, 11:10 AM
SusanZ,

Use the binomial formula to determine the probabilities for each x = 0,1,2,3,4,5,6

given n = 6, p = 0.3
q = 1-p = 0.7

P(x) = nCx = p^x * q^(n-x)

Then for each x, draw the "histogram."

For the mean and std dev you can use n*p for the mean and sqrt(n*p*q) for the std dev, or you can use the summation formulas for the expected value:

summation symbol = E

E(x * p(x))

and the variance:

E [ (x - mu)^2 * p(x) ]