7. The three volumes of Encyclopedia of Animal Kingdom sit in order on a shelf with no space between the volumes, all upright, so that their spines are visible, left to right : I, II and III. Each is 30 mm thick, comprising 24 mm of total pages and 3 mm for each cover. A bookworm bores from page 1, volume I, to the last page of volume III. How far does it travel ?

1. 90 mm

2. 36 mm

3. 72 mm

4. 84 mm

Correct Answer :

36 mm