Question 1199953
.
A bag of marbles contains seven purple, six gold and five white marbles. You select
four. How many ways are there to get at least three purple?
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<pre>
P(at least three purple) = P(three purple, 1 non-purple) + P(four purples) = 

                         = {{{C[7]^3*C[6+5]^1}}} + {{{C[7]^4}}} = 35*11 + 35 = 420.


<U>ANSWER</U>.  420 different ways.
</pre>

Solved.