Friday, April 11, 2014

Book worm

Problem :

A bookworm eats from the first page of an encyclopedia to the last page. The bookworm eats in a straight line. The encyclopedia consists of ten 1000-page volumes and is sitting on a bookshelf in the usual order. Not counting covers, title pages, etc., how many pages does the bookworm eat through?

Solution : 

On a book shelf the first page of the first volume is on the "inside"
__                             __
      B|  |                           |  |F
      A|1 |...........................|10|R
      C|  |                           |  |O
      K|  |                           |  |N
       |  |                           |  |T
       ----------------------------------
 
Remember, when the encyclopaedia is in the correct order on the bookshelf, the first volume is on the left, so the first page is not on the extreme left, nor extreme right. And also remember that he's eating from the first page to the last in a straight line, so doesn't eat either of these 2 pages.

The answer will also remain the same if you consider each sheet of paper to be two pages, he will eat 4,000 sheets of paper, which is still 8,000 pages.

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