Question 470319
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Hi,
In how many ways can 12 athletes be awarded a first-place medal, a second place medal, 
and a third-place medal?  nPx = 12P3 = {{{n!/(n-x)!)}}}= 12!/9! = 1320

In how many different ways can a student choose 3 out of 8 problems to complete
 on a take-home exam?  nCx = 8C3 = {{{n!/(x!(n-x)!)}}} = 8!/3!5! = 56

If event A is certain to occur... P(A) = 1