A box contains 3 red balls and 4 green balls. If two balls are randomly selected in sequence, what is the possibility that a red ball and a green ball are picked out of the box?

1 Answer
Feb 26, 2016

There are 3 ways to pick the red ball and 4 ways to pick the green ball for a total number of events of #3xx4=12# ways to pick a red and green ball out of the box.


There is a total of 7 balls. The sample space for the number of ways of choosing two balls is #(7!)/(2!5!)=21# ways

P(red ball and a green ball) #=12/21=4/7~~0.57#

hope that helped