A worm can gnaw through 1 mm of paper for a single day. On a bookshelf there are two volumes, each 4 cm thick. Each of the covers is 2 mm thick. How long will it take the warm to gnaw from the first page of the first volume to the last page of the second volume?

Question

anonymous · Answer

Help! my teacher gave us this brain teaser and i need a direct answer or just an explanation will do.

thesmartone · Answer

2 books means there are 4 covers.

The 4 covers are each 2mm thick.

And it takes 1 day for a worm to go through 1 mm.

thesmartone · Answer

The 2 books together are 4cm, or 40 mm.

The covers are together 4 x 2mm = 8cm.

40 - 8 = 32mm

The question asks how long it takes to go though the first page of the first volume to the last page of the second volume.

Thus the worm is not going through the first and last cover

Add 4 mm back

32 + 4 mm = 36 mm

So long will it take to go through 36 mm if the worm eats 1mm of paper a day?

anonymous · Answer

@TheSmartOne  okay but how long will it take in days? :o

anonymous · Answer

So how long in days will it take Wormy to bite through all that book and paper?

vocaloid · Answer

hint:

each book is 4 mm thick

each book also has 2 covers (back and front) which are 2 mm thick each

so, how thick is one book?

anonymous · Answer

Oh okay I think I got it xD

anonymous · Answer

Thanks :D

vocaloid · Answer

right.

it says that each cover is 2mm, but I'm not sure if that includes the front AND back, or just the front

maybe ask the teacher for clarification, if possible

thesmartone · Answer

Anytime :D