Re: Probability

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Re: Probability

You are starting out correctly, but you need to consider an arbitrary
sequence containing 4 boys and 6 girls, which would have probability
    (0.55)^4  (0.45)^6 ~= 0.000759846
Now, since there are (10 choose 4) = 210 such sequences, the probability of
exactly 4 boys is
    210* 0.000759846 ~= 0.16

============================================

From: Steve Muthler <smuthler@JSASD.K12.PA.US>
Reply-To: Steve Muthler <smuthler@JSASD.K12.PA.US>
Date: Tue, 6 Mar 2001 13:19:34 -0500
To: CALC-TI@LISTS.PPP.TI.COM
Subject: Probability


I've been wracking my brain (?!?) and can't come up with the answer to a
probability problem:

In a certain country, 55% of babies born are boys.  10 babies are born on
Jan. 1.  What is the probability that exactly 4 of them are boys?


The answer is 16%, but I have only come up with 64%.

The way I tried was this:   the probability of the first four being boys is
(.55)(.55)(.55)(.55) or .0915.

Now what?

Steve Muthler
Jersey Shore (PA) High School

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