| June
Puzzle
A wise
knight came to a bridge that spanned a deep gorge. The bridge was
guarded by an angry mathematician who required the correct answer
to a probability problem before the knight would be allowed to pass.
The knight accepted the challenge even though the penalty for a
wrong answer was clear from the pile of knights on the bottom of
the gorge.
“The
three boxes before you each contain two walking frogs,” explained
the angry mathematician. “In one box are two frogs that always
lie. Another box contains two frogs that always tell the truth.
The remaining box contains one frog that always lies and one frog
that always tells the truth.”
The
knight was then told to pick a box and then take one frog out of
the box. The knight then picked a truth-telling frog from the box
he chose. What is the probability that the remaining frog in the
box is also a “truth-teller?”
Send
your answers to Amanda Ritz at aritz@giftedstudy.com.
First correct answer receives recognition in our next edition of
The Gifted Student!
May
Puzzle:
Three
people went to lunch and bought a large meal which they all split.
The total cost, including tip, was $30. Each person paid $10 to
the waitress and started to leave the restaurant. As they left,
the waitress came running up to them with five dollars saying that
she made a mistake and that the meal and tip should have cost only
$25.
The
waitress then gave each person one dollar, but didn’t know
how to split the remaining two dollars. They told her to keep the
extra two dollars as an additional tip.
When
the people started talking about what has just happened, they started
getting confused. They had each paid $10 for the meal and received
one dollar back, so they each really paid $9 for the meal for a
total of $27. Add the two dollars of extra tip and the total is
$29. Where did the extra one dollar go?
Answer:
There
was no extra dollar. The meal was only supposed to cost $27 dollars
($25 for the meal and the $2 that they tipped the waitress). Then,
an extra dollar was given back to each of them- $27+$3 = $30. The
riddle makes you add both the amount paid and the amount received,
which doesn't work. You have to look at it from either the restaurant's
side or the customer's side, not both.
Congratulations
Ben Geilich from Hanover, New Hampshire for being the first to respond
with the correct answer! |