Plz help on this..

A class has 12 boys and 4 girls. Suppose three students are selected at random from the class. Find the probability P that they are all boys using Multiplication theorem for conditional probability.

Thnx in advance

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- Feb 7th 2008, 12:41 AMcu4mail2a. Find the Probability
Plz help on this..

A class has 12 boys and 4 girls. Suppose three students are selected at random from the class. Find the probability P that they are all boys using Multiplication theorem for conditional probability.

Thnx in advance - Feb 7th 2008, 01:13 AMDivideBy0
There are $\displaystyle {12 \choose 3}$ ways of picking 3 boys.

**AND**there are $\displaystyle {4 \choose 0}$ ways of picking 0 girls.

There are $\displaystyle {16 \choose 3}$ ways of picking three students.

So the probability is $\displaystyle \frac{{12 \choose 3} {4 \choose 0}}{{16 \choose 3}}=\frac{11}{28}$