<PRE><B>Question 1185443</B>
&lt;br&gt;
a) exactly 4 sixes&lt;br&gt;
The probability of a 6 on each roll is 1/6; the probability of any other outcome is 5/6.&lt;br&gt;
The number of orders in which you can get exactly 4 sixes in 5 rolls is C(5,4).&lt;br&gt;
P(4 sixes in 5 rolls) = {{{C(5,4)((1/6)^4)((5/6)^1)=5(5/6^5)=25/6^5=25/7776}}}&lt;br&gt;
ANSWER: 25/7776&lt;br&gt;
b) at least 4 sixes&lt;br&gt;
To the answer for part a, add the probability of getting sixes on all 5 rolls.&lt;br&gt;
P(5 sixes on 5 rolls) = {{{(1/6)^5=1/7776}}}&lt;br&gt;
ANSWER: 26/7776 (simplify if required)&lt;br&gt;
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