Question

Two urns each contain green balls and blue balls. urn i contains 4 green balls and 6 blue balls, and urn ii contains 6 green balls and 2 blue balls. a ball is drawn at random from each urn. what is the probability that both balls are blue? question 9 options:

Answer 1

4+6+6+2=18(balls)
Another way 1)4+6=10(balls)-green and blue
                      2)6+2=8(balls)-green and blue
                      3)10+8=18(balls)-total probability

Answer 2

Urn 1: P(blue) = 6/10
Urn 2: P(blue) = 2/8
The events 'draw a blue ball from urn 1' and 'draw a blue ball from urn 2' are independent. Therefore the probability that both balls are blue is the product of the two values of probability:
$P(both\ blue)=\frac{6}{10}\times\frac{2}{8}=\frac{12}{80}=\frac{3}{20}$
The answer is: 3/20.