User:Bissue

i suppose i have a user page now

2020 Apocalyptic AMC 8:

1. To walk up a single floor in her eighteen floor apartment building, Sarah needs to take nine steps up a flight of stairs. If Sarah starts on Floor $3$ and walks up $100$ steps, she would end up on the flight of stairs connecting which two floors?

$\textbf{(A)} ~ \mbox{11 and 12} \qquad \textbf{(B)} ~ \mbox{12 and 13} \qquad \textbf{(C)} ~ \mbox{13 and 14} \qquad \textbf{(D)} ~ \mbox{14 and 15} \qquad \textbf{(E)} ~ \mbox{15 and 16}$

2. Abby, Barb, and Carlos each have $35$ , $42$ , and $31$ trading cards respectively. If they share their trading cards equally between each other, how many more trading cards would Carlos have than before?

$\textbf{(A)} ~ 4 \qquad \textbf{(B)} ~ 5 \qquad \textbf{(C)} ~ 6 \qquad \textbf{(D)} ~ 9 \qquad \textbf{(E)} ~ 11$

3. In triangle $ABC$ the measure of angle $A$ is the average of the measures of angles $B$ and $C$ . What is the measure of angle $A$ ?

$\textbf{(A)} ~ 45^{\circ} \qquad \textbf{(B)} ~ 60^{\circ} \qquad \textbf{(C)} ~ 75^{\circ} \qquad \textbf{(D)} ~ 90^{\circ} \qquad \textbf{(E)} ~ 120^{\circ}$

4. A spruce tree grows by $25$ feet, increasing its height by $25 \%$ . If the tree grows for a second time by $25$ feet, by what percent would its height increase?

$\textbf{(A)} ~ 5 \% \qquad \textbf{(B)} ~ 15 \% \qquad \textbf{(C)} ~ 20 \% \qquad \textbf{(D)} ~ 25 \% \qquad \textbf{(E)} ~ 30 \%$

5. Find the sum of the digits of $\dfrac{5 \times 10^{2020}}{2}$ .

$\textbf{(A)} ~ 1 \qquad \textbf{(B)} ~ 2 \qquad \textbf{(C)} ~ 5 \qquad \textbf{(D)} ~ 7 \qquad \textbf{(E)} ~ 8$

6. Square $B$ with side length three is attached to a side of square $A$ with side length four, as shown in the figure below. Find the area of the shaded region. [center] [asy] size(150); draw((0, 0)--(4, 0)--(4, 4)--(0, 4)--cycle); draw((4, 1)--(7, 1)--(7, 4)--(4, 4)--cycle); filldraw((0, 0)--(4, 0)--(4, 2.285714)--cycle, grey); filldraw((4, 1)--(7, 1)--(7, 4)--(4, 2.285714)--cycle, grey); label("A", (2, 2)); label("B", (5.5, 2.5)); [/asy] [/center] $\textbf{(A)} ~ 10 \qquad \textbf{(B)} ~ 10 \frac{1}{2} \qquad \textbf{(C)} ~ 11 \qquad \textbf{(D)} ~ 14 \qquad \textbf{(E)} ~ 14 \frac{1}{2}$

7. When expressed as a decimal rounded to the nearest ten-thousandth, what is the value of $\dfrac{125+3}{125 \times 3}$ ?

$\textbf{(A)} ~ 0.3412 \qquad \textbf{(B)} ~ 0.3413 \qquad \textbf{(C)} ~ 0.3414 \qquad \textbf{(D)} ~ 0.3415 \qquad \textbf{(E)} ~ 0.3416$

8. What is the value of $(1+2+3)-(2+3+4)+(3+4+5)-\cdots -(98+99+100)?$ $\textbf{(A)} ~ -150 \qquad \textbf{(B)} ~ -147 \qquad \textbf{(C)} ~ -144 \qquad \textbf{(D)} ~ 147 \qquad \textbf{(E)} ~ 150$

9. Kayla writes down the first $N$ positive integers. What is the sum of all possible values of $N$ if Kayla writes five multiples of $13$ and six multiples of $12$ ?

$\textbf{(A)} ~ 447 \qquad \textbf{(B)} ~ 453 \qquad \textbf{(C)} ~ 518 \qquad \textbf{(D)} ~ 525 \qquad \textbf{(E)} ~ 548$

10. In Murphy's seventh grade homeroom, $\frac{7}{12}$ of the students like tennis, $\frac{2}{3}$ of the students like badminton, and $\frac{1}{12}$ of the students like neither. What is the minimum possible number of students who like both tennis and badminton?

$\textbf{(A)} ~ 1 \qquad \textbf{(B)} ~ 2 \qquad \textbf{(C)} ~ 3 \qquad \textbf{(D)} ~ 4 \qquad \textbf{(E)} ~ 6$

11. For how many values of $N$ does there exist a regular $N$ sided polygon whose vertices all lie on the vertices of a regular $24$ sided polygon?

$\textbf{(A)} ~ 6 \qquad \textbf{(B)} ~ 7 \qquad \textbf{(C)} ~ 8 \qquad \textbf{(D)} ~ 9 \qquad \textbf{(E)} ~ 10$

12. Quadrilateral $WXYZ$ has its vertices on the sides of rectangle $ABCD$ with $AB=7$ and $BC=5$ , as shown below. What is the area of quadrilateral $WXYZ$ ? [center] [asy] size(150); draw((0, 0)--(7, 0)--(7, 5)--(0, 5)--cycle); label("A", (0, 0), SW); label("B", (7, 0), SE); label("C", (7, 5), NE); label("D", (0, 5), NW); filldraw((0, 1)--(4, 0)--(7, 3)--(4, 5)--cycle, grey); label("W", (0, 1), W); label("X", (4, 0), S); label("Y", (7, 3), E); label("Z", (4, 5), N); label("4", (2, -0.5)); label("3", (5.5, -0.5)); label("4", (2, 5.5)); label("3", (5.5, 5.5)); [/asy] [/center] $\textbf{(A)} ~ 15 \dfrac{1}{2} \qquad \textbf{(B)} ~ 16 \qquad \textbf{(C)} ~ 16 \dfrac{1}{2} \qquad \textbf{(D)} ~ 17 \qquad \textbf{(E)} ~ 17 \dfrac{1}{2}$

13. To drive to the supermarket, Mable drives for $m$ miles, then drives $12$ miles per hour faster for the remaining $\frac{4}{3}m$ miles. The amount of time Mable spent driving at each of the two speeds was equal. What was Mable's average speed during her drive to the supermarket, in miles per hour?

$\textbf{(A)} ~ \dfrac{81}{2} \qquad \textbf{(B)} ~ \dfrac{288}{7} \qquad \textbf{(C)} ~ 42 \qquad \textbf{(D)} ~ \dfrac{300}{7} \qquad \textbf{(E)} ~ 50$

14. Six circles of radius one are cut out of the rectangle below. What is the area of the shaded region? [center] [asy] size(150); filldraw((0, 0)--(6, 0)--(6, 4)--(0, 4)--cycle, grey); filldraw(circle((1, 1), 1), white); filldraw(circle((3, 1), 1), white); filldraw(circle((5, 1), 1), white); filldraw(circle((1, 3), 1), white); filldraw(circle((3, 3), 1), white); filldraw(circle((5, 3), 1), white); [/asy] [/center] $\textbf{(A)} ~ 20-6\pi \qquad \textbf{(B)} ~ 24-6\pi \qquad \textbf{(C)} ~ 28-6\pi \qquad \textbf{(D)} ~ 30-6\pi \qquad \textbf{(E)} ~ 32-6\pi$

15. One metronome beeps at a steady rate of $72$ beeps per minute, while another metronome beeps at a steady rate of $96$ beeps per minute. If both metronomes beep at the same time once, how long will it take, in seconds, until they first beep at the same time again?

$\textbf{(A)} ~ 2 \dfrac{1}{2} \qquad \textbf{(B)} ~ 5 \qquad \textbf{(C)} ~ 10 \qquad \textbf{(D)} ~ 18 \qquad \textbf{(E)} ~ 24$

16. A square with side length two is placed on a table, forming a $30$ degree angle with the table's surface. How much higher is the top vertex of the square than the table? [center][asy] size(150); draw((0, 0)--(0.882, 0.4714)--(0.4106, 1.3534)--(-0.4714, 0.882)--cycle); draw((-0.5, 0)--(1, 0), linewidth(3)); draw((-0.75, 1.3534)--(-0.65, 1.3534)); draw((-0.7, 1.3534)--(-0.7, 0)); draw((-0.75, 0)--(-0.65, 0)); [/asy][/center] $\textbf{(A)} ~ \dfrac{5}{2} \qquad \textbf{(B)} ~ \sqrt{3}+1 \qquad \textbf{(C)} ~ \dfrac{4\sqrt{3}}{3} \qquad \textbf{(D)} ~ 3 \qquad \textbf{(E)} ~ \dfrac{3\sqrt{3}}{2}+1$

17. Kurtis' school schedule is made up of four classes, followed by lunch, followed by three more classes. In how many ways can Kurtis arrange his schedule if two of his classes (Reading and Writing) must occur one immediately after the other?

$\textbf{(A)} ~ 600 \qquad \textbf{(B)} ~ 840 \qquad \textbf{(C)} ~ 1200 \qquad \textbf{(D)} ~ 1440 \qquad \textbf{(E)} ~ 1680$

18. When the number $25$ is added to a list of numbers with total sum $S$ , the average of all the numbers increases by one. What is the sum of the digits of the greatest possible value of $S$ ?

$\textbf{(A)} ~ 6 \qquad \textbf{(B)} ~ 7 \qquad \textbf{(C)} ~ 8 \qquad \textbf{(D)} ~ 9 \qquad \textbf{(E)} ~ 12$

19. A magician randomly picks a three digit positive integer to put into her hat and pulls out the same number with its digits in reverse order. (For example $496$ would become $694$ and $720$ would become $27$ .) What is the probability the magician pulls out a multiple of $22$ ?

$\textbf{(A)} ~ \dfrac{1}{15} \qquad \textbf{(B)} ~ \dfrac{1}{18} \qquad \textbf{(C)} ~ \dfrac{1}{20} \qquad \textbf{(D)} ~ \dfrac{1}{25} \qquad \textbf{(E)} ~ \dfrac{1}{30}$

20. Tyrone has three books to read in six days. He reads one-half of a single book every day. In how many ways can he finish all the books if he may not read the same book two days in a row?

$\textbf{(A)} ~ 12 \qquad \textbf{(B)} ~ 18 \qquad \textbf{(C)} ~ 24 \qquad \textbf{(D)} ~ 30 \qquad \textbf{(E)} ~ 36$

21. There exists a circle that is tangent to $AB$ and $BC$ at $A$ and $C$ , respectively. If $AB=BC=13$ and $AC=10$ , what is the radius of the circle? [center][asy] size(150); draw((-5, 0)--(5, 0)--(0, -12)--cycle); draw(circle((0, 2.08333), 5.41666)); label("A", (-5, 0), W); label("C", (5, 0), E); label("B", (0, -12), S); label("13", (-2.7, -6), W); label("13", (2.7, -6), E); label("10", (0, 0.2), N); [/asy][/center] $\textbf{(A)} ~ \dfrac{60}{13} \qquad \textbf{(B)} ~ 5 \qquad \textbf{(C)} ~ \dfrac{26}{5} \qquad \textbf{(D)} ~ \dfrac{65}{12} \qquad \textbf{(E)} ~ \dfrac{156}{25}$

22. For each of the distinct sets of numbers containing only positive integers between $1$ and $9$ inclusive, Jordan writes the sum of the numbers in that set. What is the sum of the numbers Jordan writes?

$\textbf{(A)} ~ 11520 \qquad \textbf{(B)} ~ 11565 \qquad \textbf{(C)} ~ 11610 \qquad \textbf{(D)} ~ 11655 \qquad \textbf{(E)} ~ 11700$

23. In rectangle $ABCD$ , the perpendicular from $B$ to diagonal $AC$ bisects segment $CD$ . Which of the following is closest to $\frac{AB}{BC}$ ?

$\textbf{(A)} ~ \dfrac{5}{4} \qquad \textbf{(B)} ~ \dfrac{4}{3} \qquad \textbf{(C)} ~ \dfrac{7}{5} \qquad \textbf{(D)} ~ \dfrac{3}{2} \qquad \textbf{(E)} ~ \dfrac{8}{5}$

24. How many ordered triples of positive integers $(a, b, c)$ satisfy $\text{gcd}(a, b, c)=20$ and $\text{lcm}(a, b, c)=240$ ?

$\textbf{(A)} ~ 18 \qquad \textbf{(B)} ~ 24 \qquad \textbf{(C)} ~ 36 \qquad \textbf{(D)} ~ 54 \qquad \textbf{(E)} ~ 72$

25. Cheyanne rolls two standard six sided dice, then repeatedly rerolls all dice which show an odd number and stops as soon as all dice show an even number. What is the probability Cheyanne stops after exactly four rounds of rerolling?

$\textbf{(A)} ~ \dfrac{61}{1024} \qquad \textbf{(B)} ~ \dfrac{1}{16} \qquad \textbf{(C)} ~ \dfrac{67}{1024} \qquad \textbf{(D)} ~ \dfrac{9}{128} \qquad \textbf{(E)} ~ \dfrac{29}{256}$

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