Question 1192894
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The number of possible combinations of 3 of the 5 balls is "5 choose 3":<br>
{{{C(5,3)=C(5,2)=(5*4)/(2*1)=10}}}<br>
For the median of the three selected balls to be NOT less than 4, the median must be ball 4; that means the three balls are 4, 5, and one of the other three.  The number of combinations with that requirement is 3 choose 1, which is 3.<br>
So the probability of getting a median that is 4 is 3/10; and of course there is no way to get a median of 5.<br>
So finally the probability of the median of the three selected balls to be less than 4 is 1-3/10 = 7/10.<br>
ANSWER: 7/10<br>