Question

Thirty-one books are arranged from left to right in order of increasing prices. The price of each book differs by $2 from that of each adjacent book. For the price of the book at the extreme right, a customer can buy the middle book and a book adjacent to the middle one. Give an expression for the cost of the nth book in terms of n.

Can someone help me out? Will give medal.

Answer 1

I'm not sure if I understand you but if I did, this is what I got:

Example: Say the first book is $2. And n can mean any number but let's say 's 5. So if each book differs in the price by $2 each then the 5th book would be $10.

So let's bring it to the problem:
31 books. Well it's not a even number so let's round it to 32. So 32 divided by 2 is 16. So it's the 16th book. But each book differs by $2. 16 x 2 which brings you back to 32. $32. But is says we can adjacent it so it would be the price of 1 kind of like buy 1 get 1 free. So it would be $30.

Sorry if it's wrong. I don't understand the problem very well. What grade is this? :/