Question
An urn contains 4 red and 7 blue balls. Two balls are drawn at random with replacement. Find the probability of getting one red and one blue ball.
Solution
Number of red balls = 4
Number of blue balls = 7
Total number of balls = 4 + 7 = 11
P(one of them is red and other blue) = P(RB) + P(BR) = P(R) P(B) + P(B) P(R)
= 
