Question bank AMC12 2022

What is the value of

$$
3+\cfrac{1}{3+\cfrac{1}{3+\frac13}}?
$$

The sum of three numbers is $96.$ The first number is $6$ times the third number, and the third number is $40$ less than the second number. What is the absolute value of the difference between the first and second numbers?

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?

The least common multiple of a positive integer $n$ and $18$ is $180,$ and the greatest common divisor of $n$ and $45$ is $15.$ What is the sum of the digits of $n?$

Let the *taxicab distance* between points $(x_1,y_1)$ and $(x_2,y_2)$ in the coordinate plane be given by $|x_1-x_2|+|y_1-y_2|.$ For how many points $P$ with integer coordinates is the taxicab distance between $P$ and the origin less than or equal to $20?$

A data set consists of $6$ (not distinct) positive integers: $1,$ $7,$ $5,$ $2,$ $5,$ and $X.$ The average (arithmetic mean) of the $6$ numbers equals a value in the data set. What is the sum of all positive values of $X?$

A rectangle is partitioned into $5$ regions as shown. Each region is to be painted a solid color - red, orange, yellow, blue, or green - so that regions that touch are painted different colors, and colors can be used more than once. How many different colorings are possible?

The infinite product

$$
\sqrt[3]{10}\cdot\sqrt[3]{\sqrt[3]{10}}\cdot\sqrt[3]{\sqrt[3]{\sqrt[3]{10}}}\cdots
$$

evaluates to a real number. What is that number?

On Halloween $31$ children walked into the principal’s office asking for candy. They can be classified into three types: some always lie; some always tell the truth; and some alternately lie and tell the truth. The alternaters arbitrarily choose their first response, either a lie or the truth, but each subsequent statement has the opposite truth value from its predecessor. The principal asked everyone the same three questions in this order.

“Are you a truth-teller?” The principal gave a piece of candy to each of the $22$ children who answered yes.

“Are you an alternater?” The principal gave a piece of candy to each of the $15$ children who answered yes.

“Are you a liar?” The principal gave a piece of candy to each of the $9$ children who answered yes.

How many pieces of candy in all did the principal give to the children who always tell the truth?

What is the number of ways the numbers from $1$ to $14$ can be split into $7$ pairs such that for each pair, the greater number is at least $2$ times the smaller number?

What is the product of all real numbers $x$ such that the distance on the number line between $\log_6 x$ and $\log_6 9$ is twice the distance on the number line between $\log_6 10$ and $1?$

Let $M$ be the midpoint of $\overline{AB}$ in regular tetrahedron $ABCD.$ What is $\cos(\angle CMD)?$

Let $\mathcal{R}$ be the region in the complex plane consisting of all complex numbers $z$ that can be written as the sum of complex numbers $z_1$ and $z_2,$ where $z_1$ lies on the segment with endpoints $3$ and $4i,$ and $z_2$ has magnitude at most $1.$ What integer is closest to the area of $\mathcal{R}?$

What is the value of

$$
\begin{aligned} &(\log 5)^3+(\log 20)^3 \\ &\quad {}+(\log 8)(\log 0.25) \end{aligned}
$$

where $\log$ denotes the base-ten logarithm?

The roots of the polynomial $10x^3-39x^2+29x-6$ are the height, length, and width of a rectangular box (right rectangular prism). A new rectangular box is formed by lengthening each edge of the original box by $2$ units. What is the volume of the new box?

A *triangular number* is a positive integer that can be expressed in the form $t_n=1+2+3+\cdots+n,$ for some positive integer $n.$ The three smallest triangular numbers that are also perfect squares are $t_1=1=1^2,$ $t_8=36=6^2,$ and $t_{49}=1225=35^2.$ What is the sum of the digits of the fourth smallest triangular number that is also a perfect square?

Suppose $a$ is a real number such that the equation

$$
a\cdot(\sin x+\sin(2x))=\sin(3x)
$$

has more than one solution in the interval $(0,\pi).$ The set of all such $a$ can be written in the form $(p,q)\cup(q,r),$ where $p,$ $q,$ and $r$ are real numbers with $p\lt q\lt r.$ What is $p+q+r?$

Let $T_k$ be the transformation of the coordinate plane that first rotates the plane $k$ degrees counterclockwise around the origin and then reflects the plane across the $y$-axis. What is the least positive integer $n$ such that performing the sequence of transformations $T_1,$ $T_2,$ $T_3,$ $\ldots,$ $T_n$ returns the point $(1,0)$ back to itself?

Suppose that $13$ cards numbered $1,$ $2,$ $3,$ $\ldots,$ $13$ are arranged in a row. The task is to pick them up in numerically increasing order, working repeatedly from left to right. In the example below, cards $1,$ $2,$ $3$ are picked up on the first pass, $4$ and $5$ on the second pass, $6$ on the third pass, $7,$ $8,$ $9,$ $10$ on the fourth pass, and $11,$ $12,$ $13$ on the fifth pass. For how many of the $13!$ possible orderings of the cards will the $13$ cards be picked up in exactly two passes?

Isosceles trapezoid $ABCD$ has parallel sides $\overline{AD}$ and $\overline{BC},$ with $BC\lt AD$ and $AB=CD.$ There is a point $P$ in the plane such that $PA=1,$ $PB=2,$ $PC=3,$ and $PD=4.$ What is $\dfrac{BC}{AD}?$