The probability of getting two balls of different color is 0.268
How to find the probability?
We know that Louise has 3 yellow balls and 17 white balls in a box.
First, let's find the probability that the first ball is yellow, the probability is given by the quotient between the number of yellow balls and the total number of balls:
P = 3/20
The probability of getting another yellow ball is:
P' = 2/19 (now there are 2 yellow balls and 19 in total)
The joint probability here is:
p = (3/20)*(2/19) = 3/190
And if the two are white we will have:
Q = 17/20
Q' = 16/19
The joint probability is:
q =( 17/20)*(16/19) = 0.716
Now, the probability of getting two balls of different color is 1 minus the two probabilities we got above, it gives:
probabiltiy = 1 - 0.716 - 3/190 = 0.268
Complete question:
Louise has 3 yellow balls and 17 white balls in a box. Louise takes one ball at random from the box, keeps it, and takes another ball from the box.
Find the probability that the two balls are of different color.