Conditional probability urgent?

WE need to find the probability (

We know

P()=

First we find P(Boy)

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

So P(Boy) =

Now we find the intersection of Junior and Boy

WE look at the Junior row and boys column that is 2

{P(Junior ∩ Boy) =

P()=

P()=

= =

P() =

85.560%

step-by-step explanation:

conditional probability is defined as:

p(a|b) = p(a∩b) / p(b)

in other words, the probability that a occurs, given that b has occurred = the probability that both a and b occur / the probability that b occurs.

in this example:

p(turns 64 | turns 44) = p(turns 64 & turns 44) / p(turns 44).

if someone turns 64, they must have already turned 44, so:

p(turns 64 | turns 44) = p(turns 64) / p(turns 44)

on page 42, we see that of the original 100,000, 94944 turn 44, and 81234 turn 64.   therefore:

p(turns 64 | turns 44) = 81234 / 94944

p(turns 64 | turns 44) = 0.85560

step-by-step explanation:

a and d