How is this true? Bookworm puzzle

Question

This is from Eugene Northrop's book Riddles in Mathematics.

Why is the answer 1 inch. Iit should be three. What logic am I missing here?

Answer 1

Hint : look at the picture and consider what is the front and back of each volume.

Answer 2

Think about where the FRONT cover of volume I is and the BACK cover of volume III. It's a trick question.

Answer 3

I think according to the picture, the "front cover of volume I" is actually between the books I and II, while the back cover of volume 3 is between II and III. I think the wording is just trying to mislead the reader to think the worm eats through all the books, when it really just eats through volume II (which is the only thing between the outside of the front cover of volume I and the outside of the back cover of volume III).

Answer 4

There is no indication that these are English language books. Japanese books, for example are often bound on the right hand side. In that case, the bookworm would have to travel the full 3 inches... except that he'd probably be thinking in terms of centimetres, so about 7.6 cm.