Question

CONDITIONAL PROBABILITY ASSISTANCE?

Answer 1

WE need to find the probability ($\frac{Junior}{girl}$)

We know Probability ( $\frac{A}{B}$) = $\frac{P(A and B)}{P(B)}$

P ( $\frac{Junior}{Girl}$) = $\frac{P(Junior and girl)}{P(girl)}$

First we find P(Girl)

From the table we can see that we have 18 girls out of (12+18=30) students

So P(Girl) = $\frac{18}{30}$

Now we find the intersection of Junior and Girl

WE look at the Junior row and girls column that is 3

{P(Junior ∩ Girl) = $\frac{3}{30}$

P ( $\frac{Junior}{Girl}$) = $\frac{P(Junior and girl)}{P(girl)}$

P ( $\frac{Junior}{Girl}$) = $\frac{\frac{3}{30}}{\frac{18}{30}}$

= $\frac{3}{18} = \frac{1}{6}$