A bakery produces six different kinds of pastry, one of which is eclairs. Assume there are at least 20 pastries of each kind.
a) How many different selections of twenty pastries are there?
I was thinking combinations with repetition and order doesn't matter, so (n+r-1 r) but I'm not sure where n=120 and r=20?
b) How many different selections of twenty pastries are there if at least three must be eclairs?
(n+r-1 r) = (120+20-1 20) = (139 20) (20 3) ???
c) How many different selections of twenty pastries contain at most two eclairs?
(139 20) (20 2) ??
At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga.
Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus.
Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat.
Ask in Maths
I did :( But no one knows how to do it :/
I think the language in this one is rather confusing.
Not the answer you are looking for? Search for more explanations.
This looks like combinations and permutations. I've done those before, but it's been a few years. I think myininaya might be able to help you out. You should leave her a fan testimonial and ask her to look at this question.
I don't know if she's online right now, but she should be more than happy to help when she comes online.