2024 AMC Proposals
by djmathman, Nov 13, 2024, 11:17 PM
Four proposals this time. One great, three OK.
12A 12/10A 19. The first three terms of a geometric sequence are the integers
and
where
What is the sum of the digits of the least possible value of 
Comments
10A 22. Let
be the kite formed by joining two right triangles with legs
and
along a common hypotenuse. Eight copies of
are used to form the polygon shown below. What is the area of triangle
?
Comments
10A 25/12A 22. The figure below shows a dotted grid
cells wide and
cells tall consisting of
squares. Carl places
-inch toothpicks along some of the sides of the squares to create a closed loop that does not intersect itself. The numbers in the cells indicate the number of sides of that square that are to be covered by toothpicks, and any number of toothpicks are allowed if no number is written. In how many ways can Carl place the toothpicks?

Comments
12B 19. Equilateral
with side length
is rotated about its center by angle
, where
, to form
. See the figure. The area of hexagon
is
. What is
?
![[asy]
defaultpen(fontsize(13)); size(170);
pair O=(0,0),A=dir(225),B=dir(-15),C=dir(105),D=rotate(38.21,O)*A,E=rotate(38.21,O)*B,F=rotate(38.21,O)*C;
draw(A--B--C--A,gray+0.4);draw(D--E--F--D,gray+0.4); draw(A--D--B--E--C--F--A,black+0.9); dot(O); dot("$A$",A,dir(A)); dot("$B$",B,dir(B)); dot("$C$",C,dir(C)); dot("$D$",D,dir(D)); dot("$E$",E,dir(E)); dot("$F$",F,dir(F));
[/asy]](//latex.artofproblemsolving.com/a/7/2/a72db31d1d76e376654dd13a3f9a166d0d6056ce.png)
Comments
12A 12/10A 19. The first three terms of a geometric sequence are the integers




Comments
This is probably the most forgettable AMC problem I've written in a while. I think there are some interesting ideas in here -- the point was to figure out how to reason with geometric series having rational common ratios. I also think the number
is a good choice, because once you stumble upon
it's pretty easy to convince yourself this is optimal. But this problem doesn't really have the same "impact" as some of my previous proposals.


10A 22. Let






I had to write a problem about the aperiodic monotile that gained so much popularity in 2023. The only thing worth mentioning here is that the choice of points
,
, and
was intentional: I wanted to make sure most (if not all) of the kites were part of the triangle.
This problem was not intended for the #22 slot, and in this regard I think it was misplaced. That said, the original diagram I submitted to the AMCs did not connect the three vertices
,
, and
to form the triangle. Instead, I only gave the vertices, and it was the students' job to figure out how these points related to each other. I actually think a bit of the problem's purpose was lost with this change. Oh well.



This problem was not intended for the #22 slot, and in this regard I think it was misplaced. That said, the original diagram I submitted to the AMCs did not connect the three vertices



10A 25/12A 22. The figure below shows a dotted grid




![[asy] size(6cm); for (int i=0; i<9; ++i) { draw((i,0)--(i,3),dotted); } for (int i=0; i<4; ++i){ draw((0,i)--(8,i),dotted); } for (int i=0; i<8; ++i) { for (int j=0; j<3; ++j) { if (j==1) { label("1",(i+0.5,1.5)); }}} [/asy]](http://latex.artofproblemsolving.com/b/1/c/b1cfd38f58057d8f0ed435b054143237ba4fac8c.png)

Comments
Yea, no doubt this is my favorite proposal from this year. My original attempt for this problem used
s instead of
s along the middle, but this proved to be too annoying to work with. Changing the numbers made the problem way better than I expected. Slitherlink is a good genre.


12B 19. Equilateral








![[asy]
defaultpen(fontsize(13)); size(170);
pair O=(0,0),A=dir(225),B=dir(-15),C=dir(105),D=rotate(38.21,O)*A,E=rotate(38.21,O)*B,F=rotate(38.21,O)*C;
draw(A--B--C--A,gray+0.4);draw(D--E--F--D,gray+0.4); draw(A--D--B--E--C--F--A,black+0.9); dot(O); dot("$A$",A,dir(A)); dot("$B$",B,dir(B)); dot("$C$",C,dir(C)); dot("$D$",D,dir(D)); dot("$E$",E,dir(E)); dot("$F$",F,dir(F));
[/asy]](http://latex.artofproblemsolving.com/a/7/2/a72db31d1d76e376654dd13a3f9a166d0d6056ce.png)
Comments
Second year in a row I've written a problem about rotating a regular polygon about its center. Maybe this is a trend? Probably not. Otherwise, this problem is OK. It's not easy to figure out how to extract all the appropriate information, but in the end it seems like most people trig bashed this, which I should have expected. I have a habit of finding strange solutions to my own problems to minimize computation, because that's just how I think.
This post has been edited 2 times. Last edited by djmathman, Nov 13, 2024, 11:19 PM