Question 1150267
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There are 4 + 2 + 3 = 9 balls, in all.


The number of all pairs of balls is  {{{(9*8)/2}}} = 9*4 = 36.  (The order of balls in pairs does not matter).


The number of all pairs consisting of red balls is  {{{(4*3)/2}}} = 6.


The number of all pairs consisting of white balls is 1.


The number of all pairs consisting of green balls is  {{{(3*2)/2}}} = 3.



Thus the desired probability  is  P = {{{(6+1+3)/36}}} = {{{10/36}}} = {{{5/18}}}.    <U>ANSWER</U>
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Solved.