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2008 AMC 12B

All 25 problems from the 2008 AMC 12B. Take it as a timed mock test — 1:15:00 on the clock, scored the way the real contest is — or read through the problems and open any of them for hints and a worked solution.

25 problems · 6 points correct, 1.5 for blank, 0 for wrong

  1. A basketball player made 55 baskets during a game. Each basket was worth either 22 or 33 points. How many different numbers could represent the total points scored by the player?
  2. A 4×44 \times 4 block of calendar dates is shown. The order of the numbers in the second row is to be reversed. Then the order of the numbers in the fourth row is to be reversed. Finally, the numbers on each diagonal are to be added. What will be the positive difference between the two diagonal sums?
  3. A semipro baseball league has teams with 2121 players each. League rules state that a player must be paid at least $15,000,\$15{,}000, and that the total of all players’ salaries for each team cannot exceed $700,000.\$700{,}000. What is the maximum possible salary, in dollars, for a single player?
  4. On circle O,O, points CC and DD are on the same side of diameter AB‾,\overline{AB}, ∠AOC=30∘,\angle AOC = 30^\circ, and ∠DOB=45∘.\angle DOB = 45^\circ. What is the ratio of the area of the smaller sector CODCOD to the area of the circle?
  5. A class collects $50\$50 to buy flowers for a classmate who is in the hospital. Roses cost $3\$3 each, and carnations cost $2\$2 each. No other flowers are to be used. How many different bouquets could be purchased for exactly $50?\$50?
  6. Postman Pete has a pedometer to count his steps. The pedometer records up to 9999999999 steps, then flips over to 0000000000 on the next step. Pete plans to determine his mileage for a year. On January 11 Pete sets the pedometer to 00000.00000. During the year, the pedometer flips from 9999999999 to 0000000000 forty-four times. On December 3131 the pedometer reads 50000.50000. Pete takes 18001800 steps per mile. Which of the following is closest to the number of miles Pete walked during the year?
  7. For real numbers aa and b,b, define a$b=(a−b)2.a \$ b = (a - b)^2. What is (x−y)2$(y−x)2?(x - y)^2 \$ (y - x)^2?
  8. Points BB and CC lie on AD‾.\overline{AD}. The length of AB‾\overline{AB} is 44 times the length of BD‾,\overline{BD}, and the length of AC‾\overline{AC} is 99 times the length of CD‾.\overline{CD}. The length of BC‾\overline{BC} is what fraction of the length of AD‾?\overline{AD}?
  9. Points AA and BB are on a circle of radius 55 and AB=6.AB = 6. Point CC is the midpoint of the minor arc AB.AB. What is the length of the line segment AC?AC?
  10. Bricklayer Brenda would take 99 hours to build a chimney alone, and bricklayer Brandon would take 1010 hours to build it alone. When they work together, they talk a lot, and their combined output is decreased by 1010 bricks per hour. Working together, they build the chimney in 55 hours. How many bricks are in the chimney?
  11. A cone-shaped mountain has its base on the ocean floor and has a height of 80008000 feet. The top 18\tfrac{1}{8} of the volume of the mountain is above water. What is the depth of the ocean at the base of the mountain, in feet?
  12. For each positive integer n,n, the mean of the first nn terms of a sequence is n.n. What is the 20082008th term of the sequence?
  13. Vertex EE of equilateral △ABE\triangle ABE is in the interior of unit square ABCD.ABCD. Let RR be the region consisting of all points inside ABCDABCD and outside △ABE\triangle ABE whose distance from AD‾\overline{AD} is between 13\tfrac{1}{3} and 23.\tfrac{2}{3}. What is the area of R?R?
  14. A circle has a radius of log⁡10(a2)\log_{10}(a^2) and a circumference of log⁡10(b4).\log_{10}(b^4). What is log⁡ab?\log_a b?
  15. On each side of a unit square, an equilateral triangle of side length 11 is constructed. On each new side of each equilateral triangle, another equilateral triangle of side length 11 is constructed. The interiors of the square and the 1212 triangles have no points in common. Let RR be the region formed by the union of the square and all the triangles, and let SS be the smallest convex polygon that contains R.R. What is the area of the region that is inside SS but outside R?R?
  16. A rectangular floor measures aa feet by bb feet, where aa and bb are positive integers with b>a.b \gt a. An artist paints a rectangle on the floor with the sides of the rectangle parallel to the sides of the floor. The unpainted part of the floor forms a border of width 11 foot around the painted rectangle and occupies half the area of the entire floor. How many possibilities are there for the ordered pair (a,b)?(a, b)?
  17. Let A,A, BB and CC be three distinct points on the graph of y=x2y = x^2 such that line ABAB is parallel to the xx-axis and △ABC\triangle ABC is a right triangle with area 2008.2008. What is the sum of the digits of the yy-coordinate of C?C?
  18. A pyramid has a square base ABCDABCD and vertex E.E. The area of square ABCDABCD is 196,196, and the areas of △ABE\triangle ABE and △CDE\triangle CDE are 105105 and 91,91, respectively. What is the volume of the pyramid?
  19. A function ff is defined by f(z)=(4+i)z2+αz+γf(z) = (4 + i)z^2 + \alpha z + \gamma for all complex numbers z,z, where α\alpha and γ\gamma are complex numbers and i2=−1.i^2 = -1. Suppose that f(1)f(1) and f(i)f(i) are both real. What is the smallest possible value of ∣α∣+∣γ∣?|\alpha| + |\gamma|?
  20. Michael walks at the rate of 55 feet per second on a long straight path. Trash pails are located every 200200 feet along the path. A garbage truck travels at 1010 feet per second in the same direction as Michael and stops for 3030 seconds at each pail. As Michael passes a pail, he notices the truck ahead of him just leaving the next pail. How many times will Michael and the truck meet?
  21. Two circles of radius 11 are to be constructed as follows. The center of circle AA is chosen uniformly and at random from the line segment joining (0,0)(0, 0) to (2,0).(2, 0). The center of circle BB is chosen uniformly and at random, and independently of the first choice, from the line segment joining (0,1)(0, 1) to (2,1).(2, 1). What is the probability that circles AA and BB intersect?
  22. A parking lot has 1616 spaces in a row. Twelve cars arrive, each of which requires one parking space, and their drivers choose their spaces at random from among the available spaces. Auntie Em then arrives in her SUV, which requires 22 adjacent spaces. What is the probability that she is able to park?
  23. The sum of the base-1010 logarithms of the divisors of 10n10^n is 792.792. What is n?n?
  24. Let A0=(0,0).A_0 = (0, 0). Distinct points A1,A_1, A2,A_2, …\ldots lie on the xx-axis, and distinct points B1,B_1, B2,B_2, …\ldots lie on the graph of y=x.y = \sqrt{x}. For every positive integer n,n, An−1BnAnA_{n-1}B_nA_n is an equilateral triangle. What is the least nn for which the length A0An≥100?A_0A_n \ge 100?
  25. Let ABCDABCD be a trapezoid with AB∥CD,AB \parallel CD, AB=11,AB = 11, BC=5,BC = 5, CD=19,CD = 19, and DA=7.DA = 7. Bisectors of ∠A\angle A and ∠D\angle D meet at P,P, and bisectors of ∠B\angle B and ∠C\angle C meet at Q.Q. What is the area of hexagon ABQCDP?ABQCDP?

0 of 25 answered. Each problem left blank still scores 1.5 points.

Practise one problem at a time, with hints and solutions, on the practice page. Or work through the same ideas across every year by topic, or browse the full AMC 12 archive.