Chapter 10: Brainteasers 355
Bookworm There is a two-volume book set on a shelf,
the volumes being side by side, first then second. The
pages of each volume are two centimeters thick and
each cover is two millimeters thick. A worm has nibbled
the set, perpendicularly to the pages, from the first page
of the first volume to the last page of the second one.
What is the length of the path he has nibbled?
(Thanks to Vito.)
Compensation A number of quants are at dinner, and
start discussing compensation. They want to calculate
the average compensation among themselves, but are
too embarrassed to disclose their own salaries. How
can they determine the average compensation of their
group? They do not have pens or paper or any other
way of writing down their salaries.
(Thanks to Arroway.)
Einstein’s brainteaser There are five houses of five differ-
ent colours. In each house lives a person of a different
nationality. Those five people drink different drinks,
smoke cigarettes of a different brand and have a differ-
ent pet. None of them has the same pet, smokes the
same cigarette or drinks the same drink.
We know:
- The Englishman lives in the red house.
- The Swede has a dog as a pet.
- The Dane drinks tea.
- The green house is on the left of the white one.
- The person who lives in the green house drinks
coffee. - The person who smokes Pall Mall raises birds.
- The owner of the yellow house smokes Dunhill.
- The man who lives in the house that is in the middle
drinks milk.