Carcass wrote:
Two children, one from each grade, will be chosen at random from 4 children from the 5th grade class and 4 children from the 4th grade class to win a prize. Each class has 3 eligible girls and one eligible boy. What is the probability that one boy and one girl will be chosen?
A. 1/2
B. 3/8
C. 3/5
D. 1/4
E. 1/8
We can select 1 boy and 1 girl in two ways:
1) select boy from 4th-grade class and girl from 5th grade class
2) select girl from 4th-grade class and boy from 5th grade class
So, P(1 boy and 1 girl) = P(boy from 4th grade
AND girl from 5th grade
OR girl from 4th grade
AND boy from 5th grade)
= P(boy from 4th grade)
x P(girl from 5th grade)
+ P(girl from 4th grade)
x P(boy from 5th grade)
= 1/4
x 3/4
+ 3/4
x 1/4
= 3/16
+ 3/16
= 6/16
= 3/8
Answer: B
Cheers,
Brent