Answer + Step-by-step explanation:
<u><em>p(X=3) = the probability that X is equal to 1 or 2 or 3 minus (the probability that X is equal to 2 plus the probability that X is equal to 1)</em></u>
<u><em>Because ,when X = 2 or X = 1 the largest number is not 3 so we have to subtract those values</em></u> .
……………………………………………………………
the probability that X is equal to 1 or 2 or 3 is :

Then

<u><em>Verification</em></u>:
1+15+65+175+369+671 = 1 296