<PRE><B>Question 1186814</B>
&lt;br&gt;
The solution from the other tutor shows finding the answer using the C(n,r) formula.&lt;br&gt;
There is another basic method that obtains the answer with far less work.&lt;br&gt;
Consider drawing the 4 balls from the bowl one at a time....&lt;br&gt;
(1) first ball -- there are 20 balls in the bowl; we can pick any of them; P=20/20
(2) second ball -- there are 19 balls left, of which 3 match the first ball; P=3/19
(3) third ball -- there are 18 balls left, of which 2 match the first ball; P=2/18
(4) fourth ball -- there are 17 balls left, of which only 1 matches the first ball; P=1/17&lt;br&gt;
The probability of drawing four matching balls is&lt;br&gt;
{{{(20/20)(3/19)(2/18)(1/17) = 1/969}}}&lt;br&gt;
ANSWER: 1/969&lt;br&gt;

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