dan's math@home - problem of the week - archives
 
 
Problem Archives page 19
Problems Only. For answers & winners click here.
 
1-10 . 11-20 . 21-30 . 31-40 . 41-50 . 51-60 . 61-70 . 71-80 . 81-90 . 91-100
101-110 . 111-120 . 121-130 . 131-140 . 141-150 . 151-160 . 161-170 . 171-180
181-190 . 191-200 . 201-210 . 211-220 . 221-230 . 231+ . prob index
 
181 - A Triangular Duel
182 - Two More Trains
183 WhichKindaCandy
184 Crank Out Power(s)
185 - Money-Go-Round
186- Sums of 2 Squares
187 - Right Triang Spiral
188- Chess Tournament
189- - -The Three Trees
190 -- The Flower Farm
 
 
Problem #181 - Posted Friday, August 29, 2003
The Triangular Duel . (back to top)
(Next-to-last problem in the sixth annual contest. Seventh Season Starts with Prob 183!
Three
men: Fermat,
Galois, and Hilbert,
decide to fight a pistol duel.
They'll stand at the corners of an
equilateral triangle, and each man, in
order, will aim and shoot wherever he pleases.
They choose randomly who will be shooting first,
second, and third, and will continue in order until two
of them are dead. All three know Fermat always hits his
target, Galois is 80% accurate, and Hilbert hits his mark half
the time. Assuming that all three adopt the best strategy and that
nobody is killed by a wild shot not intended for him, who has the best
chance to survive, and why? 1 bonus pt: find the survival probabilities for each man.
Explain your reasoning carefully. Bonus answer not req'd. One pt penalty for resubmissions.
 
Who is most likely to survive?
 
 
Problem #182 - Posted Friday, September 12, 2003
Two More Trains! . (back to top)
(Last problem in the sixth annual contest! Seventh Season Starts next week with Prob 183!)
Every algebra class is required by law to have a "two trains" problem.
But this one doesn't involve distance, rate, or time!
A short freight train, made up of an engine and five boxcars, stops at
a small station. The station has a small siding that can hold three cars,
or an engine and two cars. A long passenger train is approaching from
behind, going the same direction. How can they let the passenger train
through, and then put the freight train back just the way it was ?
 
 
 
Problem #183 - Posted Wednesday, September 24, 2003
Which Kinda Candy? . (back to top)
(First problem in my seventh annual contest!)
The labels on these boxes of candy got so mixed up that none of the
boxes is labeled correctly. What is the least number of candies you must
taste test, and from which box(es), to determine which box has what?
Explain your reasoning carefully.

3 chocolates
3 cremes
2 chocolates 1 creme
 
Problem #184 - Posted Sunday, October 5, 2003
Crank Out Power(s)! . (back to top)
Here are a couple of innocent polynomial questions 4U:
(answer both questions to be ranked as correct; explain your reasoning carefully. n^p means n to the power p)
 i) If we know x + y = 1 ,
and also x^2 + y^2 = 2,
then what is x^3 + y^3 ?
ii) We have a + b + c = 1 ,
and a^2 + b^2 + c^2 = 2,
and a^3 + b^3 + c^3 = 3,
What is a^4 + b^4 + c^4 ?
 
 
Problem #185 - Posted Saturday, October 18, 2003
Money-Go-Round! . (back to top)
Some card players sat in a circle, so that each had two neighbors, and each had a certain
number of dollars. The 1st player had $1 more than the 2nd player, who had $1 more than
the third, and so on. The first player gave $1 to the second, who gave $2 to the third, and
so on, each giving $1 more than they received, around and around the table as long as possible.
There were then 2 neighbors, one having 4 times as much money as the other.
(a) How many players were there? (b) How much money did the first player start with?
Explain your reasoning carefully.
 
 
Problem #186 - Posted Thursday, October 30, 2003
Sums of Two Squares.(meaning the sum of the squares of two positive integers) (back to top)
a) Prove that the sum of two squares, multiplied by the sum of two squares, is the sum
of two squares. b) Prove the sum of two different squares, multiplied by the sum of
two different squares, can be written as the sum of two squares in two different ways.
c) Give the smallest three examples (each) of a) and b). Explain algebra or reasoning carefully.
 
Problem #187 - Posted Tuesday, November 11, 2003
Right Triangle Spiral (back to top)
This problem still open! 1 point max while this sentence is up.
a) How many triangles will it take to go all
the way around and overlap the first?
b) Will the pattern go around and around forever,
or is there a limit to the number of rotations?
Prove your answers, explain carefully.

 
Problem #188 - Posted Friday, November 21, 2003
Chess Tournament! (back to top)
I was on my junior-high chess team! One time, another seventh grader and I entered
an eighth-grade tournament. Every player played every other player once (round-robin);
a win counted as one point and a draw was 1/2 point. My friend and I got a total of 8
points, while all the 8th-graders got the same number of points (as each other).
How many eighth-graders were in the tourney, and why?
Prove your answers, explain carefully.
 
 
Problem #189 - Posted Tuesday, December 2, 2003
The Three Trees (back to top)
Driving out in the "Western Plains" states of the U.S. is like being on a flat, infinite plane.
Three trees are now growing at random points on the plane (or plain).
What's the probability they form an obtuse triangle? Prove your answers, explain carefully.
 
 
Problem #190 - Posted Tuesday, December 23, 2003
The Flower Farm (back to top)
In the comic strip 'Foxtrot' (Nov. 3, 2003), a math tutor solves a problem about planting
as many flowers as possible in an 8m by 10m garden,where each flower was at least
1m away from the closest other flower. Apparently, his solution (shown at right) had 99
flowers (planting at the edge is ok). Can you do better? If so, give the maximum number
of flowers you can plant and show how it's done; if not, try to prove 99 is the maximum.
Prove answer, explain carefully. 1m = 1 meter.
99 and counting...
 
 
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YOU CAN ALWAYS FIND ME AT dansmath.com - Dan the Man Bach - 2003 A.D.
 
 
Problem Archives Index
 
Probs & answers . 1-10 . 11-20 . 21-30 . 31-40 . 41-50 . 51-60 . 61-70 . 71-80 . 81-90 . 91-100
Problems only . . . 1-10 . 11-20 . 21-30 . 31-40 . 41-50 . 51-60 . 61-70 . 71-80 . 81-90 . 91-100
Probs & answers . 101-110 . 111-120 . 121-130 . 131-140 . 141-150 . 151-160 . 161-170 . 171-180
Problems only . . . 101-110 . 111-120 . 121-130 . 131-140 . 141-150 . 151-160 . 161-170 . 171-180
Probs & answers . 181-190 . 191-200 . 201-210 . 211-220 . 221-230 . 231+
Problems only . . . . 181-190 . 191-200 . 201-210 . 211-220 . 221-230 . 231+
 
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