A Bookworm’s meal (Posted on 2002-04-19)

A bookworm can chew through a millimiter (mm) of paper or cardboard in half an hour. One day it encounters a particularly tasty treat: a two-volume edition of a large book standing on a shelf as shown.

The volumes are identical in size, each has a front and a back cover that is a millimeter thick on each side, and the pages of each are a 10mm thick stack of paper from the first page to the last.

If a bookworm starts its meal on the first page of the first volume (already inside the front cover), how long will it take to eat his way through to the last page of the second volume (inside the second volume’s back cover)?

	Submitted by levik
Rating: 3.2857 (7 votes)
Solution:	(Hide)
The trick to this problem is to realize that when the books are arranged in the manner shown, the back of the second book is actually in direct contact with the front of the first book. This is actually the normal way that books are displayed. The picture shows why this is true, but you can see for yourself by putting any two volumes together in order. So rather than having to eat through two sets of pages and two covers, the worm's meal is actually much shorter - consisting of the front cover of the first book and the back cover of the second book. Together they are 2 millimeters thick, so the worm will spend only 1 hour on the meal, not 11 hours as you may initially think.

	Subject	Author	Date
	Puzzle Solution	K Sengupta	2008-07-02 12:48:10
	Answer	K Sengupta	2008-07-01 06:24:48
	Simple but I bet it trips some people up	cyclothymic	2008-06-27 16:26:49
	Not enough definitive information.... (Spoiler)	Dej Mar	2008-06-27 12:21:24
	re: its either ez or im dum	Peter	2004-05-13 19:59:21
	its either ez or im dum	Peter	2004-05-13 19:57:26
	Voila!	Eric	2003-10-22 21:24:50
	re: answet	Sam	2003-09-08 23:00:02
	Simple	Alan	2003-01-09 12:45:35
	should this be in tricks?	James	2002-10-26 18:11:42
	if you were a bookworm...	Carey	2002-05-31 02:30:26
	answet	theBal	2002-05-09 13:55:00