There ar 72 coins total
a) (15+30)/72
b) the possible ways of choosing 3 coins is 72-choose-3 = 72!/3!(72-3)! = 70*71*72/6. This is the denominator.
There are 15-choose-2 ways of picking the two loonies and 30-choose-1 ways of picking the quarter. So, the numerator is ((14*15)/2))*30
Tasha has a piggy bank that contains 15 loonies, 30 quarters, 20 dimes, and 7 nickels.
a) if she chooses one con at a random to buy some candy, what is the probability of choosing a loonie or quarter?
b) if she chooses three coins, all at once , what is the probability of choosing 2 loonies and quarter?
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