SOLUTION: Suppose 500 coins are tossed. Using the normal curve approximation to the binomial distribution, find the probability of getting 251 heads or less.

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Question 165389: Suppose 500 coins are tossed. Using the normal curve approximation to the binomial distribution, find the probability of getting 251 heads or less.
Answer by Edwin McCravy(20059) About Me  (Show Source):
You can put this solution on YOUR website!
Suppose 500 coins are tossed. Using the normal curve approximation to the binomial distribution, find the probability of getting 251 heads or less.

n = 500, 
p = .5,
q = 1-.5 = .5,
x = 251.5 

(Since it included 251 we add .5, if it had not
 included 251 we would have subtracted .5)

mu=np=%28500%29%28.5%29=250

sigma=sqrt%28npq%29=sqrt%28%28500%29%280.5%29%280.5%29%29=sqrt%28125%29=11.18034

z=%28x-mu%29%2Fsigma+=+%28251.5-250%29%2F11.18034=1.5%2F11.18034=0.1331

So look up 0.13 in a standard normal table.

There are two kinds of tables.

In one kind of table you will read 0.0517 and you have to add .5
to get 0.5517.

In the other kind of table you will get 0.5517 directly.

Edwin