In a box, there are 10 red, 6 blue and 5 green balls. One ball is picked up randomly. What is the probability that it is neither red nor green ?  Pick:
A) 4/51
B) 10/21
C) 7/12
D) 5/21
E) 13/17
Total number of balls = 10+6+5= 
<gadget id="calculator">10+6+5</gadget>
<output>21</output>
21   E= event that the ball drawn is neither red nor green   = event that the ball drawn is green   n(E) = 5   P(E) = 5/21   Answer is 5/21
<result>D</result>
In a box, there are 10 red, 6 blue and 5 green balls. One ball is picked up randomly. What is the probability that it is neither red nor green ?