Found problems: 3632
2021 AIME Problems, 12
Let $A_1A_2A_3...A_{12}$ be a dodecagon (12-gon). Three frogs initially sit at $A_4,A_8,$ and $A_{12}$. At the end of each minute, simultaneously, each of the three frogs jumps to one of the two vertices adjacent to its current position, chosen randomly and independently with both choices being equally likely. All three frogs stop jumping as soon as two frogs arrive at the same vertex at the same time. The expected number of minutes until the frogs stop jumping is $\frac mn$, where $m$ and $n$ are relatively prime positive integers. Find $m+n$.
1988 AMC 12/AHSME, 5
If $b$ and $c$ are constants and \[(x + 2)(x + b) = x^2 + cx + 6,\] then $c$ is
$ \textbf{(A)}\ -5\qquad\textbf{(B)}\ -3\qquad\textbf{(C)}\ -1\qquad\textbf{(D)}\ 3\qquad\textbf{(E)}\ 5 $
1998 AMC 8, 9
For a sale, a store owner reduces the price of a $10$ dollar scarf by $20\%$. Later the price is lowered again, this time by one-half the reduced price. The price is now
$ \text{(A)}\ 2.00\text{ dollars}\qquad\text{(B)}\ 3.75\text{ dollars}\qquad\text{(C)}\ 4.00\text{ dollars}\qquad\text{(D)}\ 4.90\text{ dollars}\qquad\text{(E)}\ 6.40\text{ dollars} $
2009 AMC 10, 11
How many $ 7$ digit palindromes (numbers that read the same backward as forward) can be formed using the digits $ 2$, $ 2$, $ 3$, $ 3$, $ 5$, $ 5$, $ 5$?
$ \textbf{(A)}\ 6 \qquad \textbf{(B)}\ 12 \qquad \textbf{(C)}\ 24 \qquad \textbf{(D)}\ 36 \qquad \textbf{(E)}\ 48$
2009 AMC 10, 14
Four congruent rectangles are placed as shown. The area of the outer square is $ 4$ times that of the inner square. What is the ratio of the length of the longer side of each rectangle to the length of its shorter side?
[asy]unitsize(6mm);
defaultpen(linewidth(.8pt));
path p=(1,1)--(-2,1)--(-2,2)--(1,2);
draw(p);
draw(rotate(90)*p);
draw(rotate(180)*p);
draw(rotate(270)*p);[/asy]$ \textbf{(A)}\ 3 \qquad \textbf{(B)}\ \sqrt {10} \qquad \textbf{(C)}\ 2 \plus{} \sqrt2 \qquad \textbf{(D)}\ 2\sqrt3 \qquad \textbf{(E)}\ 4$
2009 AIME Problems, 8
Let $ S \equal{} \{2^0,2^1,2^2,\ldots,2^{10}\}$. Consider all possible positive differences of pairs of elements of $ S$. Let $ N$ be the sum of all of these differences. Find the remainder when $ N$ is divided by $ 1000$.
2023 AIME, 7
Call a positive integer $n$ [i]extra-distinct[/i] if the remainders when $n$ is divided by $2, 3, 4, 5,$ and $6$ are distinct. Find the number of extra-distinct positive integers less than $1000$.
1967 AMC 12/AHSME, 19
The area of a rectangle remains unchanged when it is made $2 \frac{1}{2}$ inches longer and $\frac{2}{3}$ inch narrower, or when it is made $2 \frac{1}{2}$ inches shorter and $\frac{4}{3}$ inch wider. Its area, in square inches, is:
$\textbf{(A)}\ 30\qquad
\textbf{(B)}\ \frac{80}{3}\qquad
\textbf{(C)}\ 24\qquad
\textbf{(D)}\ \frac{45}{2}\qquad
\textbf{(E)}\ 20$
2015 AMC 10, 1
What is the value of $2-(-2)^{-2}$?
$ \textbf{(A) } -2
\qquad\textbf{(B) } \dfrac{1}{16}
\qquad\textbf{(C) } \dfrac{7}{4}
\qquad\textbf{(D) } \dfrac{9}{4}
\qquad\textbf{(E) } 6
$
2010 Contests, 1
Determine all integer numbers $n\ge 3$ such that the regular $n$-gon can be decomposed into isosceles triangles by non-intersecting diagonals.
1971 AMC 12/AHSME, 22
If $w$ is one of the imaginary roots of the equation $x^3=1$, then the product $(1-w+w^2)(1+w-w^2)$ is equal to
$\textbf{(A) }4\qquad\textbf{(B) }w\qquad\textbf{(C) }2\qquad\textbf{(D) }w^2\qquad \textbf{(E) }1$
1978 AMC 12/AHSME, 18
What is the smallest positive integer $n$ such that $\sqrt{n}-\sqrt{n-1}<.01$?
$\textbf{(A) }2499\qquad\textbf{(B) }2500\qquad\textbf{(C) }2501\qquad\textbf{(D) }10,000\qquad \textbf{(E) }\text{There is no such integer}$
2024 AMC 10, 6
A rectangle has integer side lengths and an area of $2024$. What is the least possible perimeter of the rectangle?
$
\textbf{(A) }160 \qquad
\textbf{(B) }180 \qquad
\textbf{(C) }222 \qquad
\textbf{(D) }228 \qquad
\textbf{(E) }390 \qquad
$
1987 AMC 12/AHSME, 29
Consider the sequence of numbers defined recursively by $t_1=1$ and for $n>1$ by $t_n=1+t_{(n/2)}$ when $n$ is even and by $t_n=\frac{1}{t_{(n-1)}}$ when $n$ is odd. Given that $t_n=\frac{19}{87}$, the sum of the digits of $n$ is
$ \textbf{(A)}\ 15 \qquad\textbf{(B)}\ 17 \qquad\textbf{(C)}\ 19 \qquad\textbf{(D)}\ 21 \qquad\textbf{(E)}\ 23$
2016 AMC 12/AHSME, 10
A quadrilateral has vertices $P(a,b)$, $Q(b,a)$, $R(-a, -b)$, and $S(-b, -a)$, where $a$ and $b$ are integers with $a>b>0$. The area of $PQRS$ is $16$. What is $a+b$?
$\textbf{(A)}\ 4 \qquad\textbf{(B)}\ 5 \qquad\textbf{(C)}\ 6 \qquad\textbf{(D)}\ 12 \qquad\textbf{(E)}\ 13$
1971 AMC 12/AHSME, 12
For each integer $N>1$, there is a mathematical system in which two or more positive integers are defined to be congruent if they leave the same non-negative remainder when divided by $N$. If $69,90,$ and $125$ are congruent in one such system, then in that same system, $81$ is congruent to
$\textbf{(A) }3\qquad\textbf{(B) }4\qquad\textbf{(C) }5\qquad\textbf{(D) }7\qquad \textbf{(E) }8$
1989 AMC 12/AHSME, 9
Mr. and Mrs. Zeta want to name their baby Zeta so that its monogram (first, middle, and last initials) will be in alphabetical order with no letter repeated. How many such monograms are possible?
$\text{(A)} \ 276 \qquad \text{(B)} \ 300 \qquad \text{(C)} \ 552 \qquad \text{(D)} \ 600 \qquad \text{(E)} \ 15600$
1964 AMC 12/AHSME, 24
Let $y=(x-a)^2+(x-b)^2, a, b$ constants. For what value of $x$ is $y$ a minimum?
$ \textbf{(A)}\ \frac{a+b}{2} \qquad\textbf{(B)}\ a+b \qquad\textbf{(C)}\ \sqrt{ab} \qquad\textbf{(D)}\ \sqrt{\frac{a^2+b^2}{2}}\qquad\textbf{(E)}\ \frac{a+b}{2ab} $
1986 AMC 12/AHSME, 7
The sum of the greatest integer less than or equal to $x$ and the least integer greater than or equal to $x$ is $5$. The solution set for $x$ is
$ \textbf{(A)}\ \Big\{\frac{5}{2}\Big\}\qquad\textbf{(B)}\ \big\{x\ |\ 2 \le x \le 3\big\}\qquad\textbf{(C)}\ \big\{x\ |\ 2\le x < 3\big\}\qquad \\ \textbf{(D)}\ \Big\{x\ |\ 2 < x \le 3\Big\}\qquad\textbf{(E)}\ \Big\{x\ |\ 2 < x < 3\Big\} $
2012 AIME Problems, 9
Let $x$, $y$, and $z$ be positive real numbers that satisfy \[ 2\log_x(2y) = 2\log_{2x}(4z) = \log_{2x^4}(8yz) \neq 0. \] The value of $xy^5z$ can be expressed in the form $\frac{1}{2^{p/q}}$, where $p$ and $q$ are relatively prime integers. Find $p+q$.
2022 AMC 12/AHSME, 3
Five rectangles, $A$, $B$, $C$, $D$, and $E$, are arranged in a square as shown below. These rectangles have dimensions $1\times6$, $2\times4$, $5\times6$, $2\times7$, and $2\times3$, respectively. (The figure is not drawn to scale.) Which of the five rectangles is the shaded one in the middle?
[asy]
fill((3,2.5)--(3,4.5)--(5.3,4.5)--(5.3,2.5)--cycle,mediumgray);
draw((0,0)--(7,0)--(7,7)--(0,7)--(0,0));
draw((3,0)--(3,4.5));
draw((0,4.5)--(5.3,4.5));
draw((5.3,7)--(5.3,2.5));
draw((7,2.5)--(3,2.5));
[/asy]
$\textbf{(A) }A\qquad\textbf{(B) }B \qquad\textbf{(C) }C \qquad\textbf{(D) }D\qquad\textbf{(E) }E$
2015 AMC 10, 16
If $y+4 = (x-2)^2, x+4 = (y-2)^2$, and $x \neq y$, what is the value of $x^2+y^2$?
$ \textbf{(A) }10\qquad\textbf{(B) }15\qquad\textbf{(C) }20\qquad\textbf{(D) }25\qquad\textbf{(E) }\text{30} $
1991 AIME Problems, 15
For positive integer $n$, define $S_n$ to be the minimum value of the sum \[ \sum_{k=1}^n \sqrt{(2k-1)^2+a_k^2}, \] where $a_1,a_2,\ldots,a_n$ are positive real numbers whose sum is 17. There is a unique positive integer $n$ for which $S_n$ is also an integer. Find this $n$.
2002 AMC 8, 20
The area of triangle $ XYZ$ is 8 square inches. Points $ A$ and $ B$ are midpoints of congruent segments $ \overline{XY}$ and $ \overline{XZ}$. Altitude $ \overline{XC}$ bisects $ \overline{YZ}$. What is the area (in square inches) of the shaded region?
[asy]/* AMC8 2002 #20 Problem */
draw((0,0)--(10,0)--(5,4)--cycle);
draw((2.5,2)--(7.5,2));
draw((5,4)--(5,0));
fill((0,0)--(2.5,2)--(5,2)--(5,0)--cycle, mediumgrey);
label(scale(0.8)*"$X$", (5,4), N);
label(scale(0.8)*"$Y$", (0,0), W);
label(scale(0.8)*"$Z$", (10,0), E);
label(scale(0.8)*"$A$", (2.5,2.2), W);
label(scale(0.8)*"$B$", (7.5,2.2), E);
label(scale(0.8)*"$C$", (5,0), S);
fill((0,-.8)--(1,-.8)--(1,-.95)--cycle, white);[/asy]
$ \textbf{(A)}\ 1\frac12\qquad\textbf{(B)}\ 2\qquad\textbf{(C)}\ 2\frac12\qquad\textbf{(D)}\ 3\qquad\textbf{(E)}\ 3\frac12$
1997 AMC 8, 10
What fraction of this square region is shaded? Stripes are equal in width, and the figure is drawn to scale.
[asy]
unitsize(8);
fill((0,0)--(6,0)--(6,6)--(0,6)--cycle,black);
fill((0,0)--(5,0)--(5,5)--(0,5)--cycle,white);
fill((0,0)--(4,0)--(4,4)--(0,4)--cycle,black);
fill((0,0)--(3,0)--(3,3)--(0,3)--cycle,white);
fill((0,0)--(2,0)--(2,2)--(0,2)--cycle,black);
fill((0,0)--(1,0)--(1,1)--(0,1)--cycle,white);
draw((0,6)--(0,0)--(6,0));
[/asy]
$\textbf{(A)}\ \dfrac{5}{12} \qquad \textbf{(B)}\ \dfrac{1}{2} \qquad \textbf{(C)}\ \dfrac{7}{12} \qquad \textbf{(D)}\ \dfrac{2}{3} \qquad \textbf{(E)}\ \dfrac{5}{6}$