There are 21 balls in a box: 8 balls are green, 8 are blue and 5 are white. Then 1 green and 1 blue balls are taken from the box and put away. What is the probability that a blue ball is selected at random from the box? Pick
A) 1/13
B) 4/13
C) 3/13
D) 5/19
E) 6/13
If 1 green and 1 blue ball are taken from the box, then there are 7 green, 7 blue and 5 white balls, a total of 19 balls. If one ball is selected at random, the probability that it is white is given by   5/19   Answer : 5/19
<result>D</result>
There are 21 balls in a box: 8 balls are green, 8 are blue and 5 are white. Then 1 green and 1 blue balls are taken from the box and put away. What is the probability that a blue ball is selected at random from the box?