SOLUTION: A box contains blue and green balls in the ratio 3:4. If there are 21 balls in the box and 2 balls are drawn one after the other without replacement, what is the probability that

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Question 1191815: A box contains blue and green balls in the ratio 3:4. If there
are 21 balls in the box and 2 balls are drawn one after the
other without replacement, what is the probability that the 2
balls are of the same colour?

Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
3:4=3x:4x and their sum is 21
x=3
there are 9 blue balls and 12 green ones
same color
both blue (9/21)(8/20)=72/420
both green (12/21)(11/20)=132/420
answer is the sum or 204/420=17/35