SOLUTION: 1.A very small library has only 4 books that you can borrow.the library allows you to borrow 1,2,3 or 4 books at a time.assuming tha you borrow at least one book ,how many differen

Question 1020410: 1.A very small library has only 4 books that you can borrow.the library allows you to borrow 1,2,3 or 4 books at a time.assuming tha you borrow at least one book ,how many different selections can you make?
2. Lisa makek up a series of numbers.he finds each number in the series by multiplying the previous number by 3 & adding 5.if his fifth number is 767, what must his first number have been?
Please help me
Answer by ikleyn(52781) (Show Source): You can put this solution on YOUR website!
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1.A very small library has only 4 books that you can borrow.the library allows you to borrow 1,2,3 or 4 books at a time.
Assuming that you borrow at least one book ,how many different selections can you make?
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It is the same as to ask: how many non-empty subsets are there in the set of 4 elements.

The answer is = 15.

For details, see the lesson How many subsets are there in a given finite set of n elements? in this site.

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