Mini mock 2
15 problems matching a real contest's position mix, 45 minutes
- 1.2016 AMC 10A #1
What is the value of ?
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- 2.2013 AMC 10A #2
Alice is making a batch of cookies and needs cups of sugar. Unfortunately, her measuring cup holds only cup of sugar. How many times must she fill that cup to get the correct amount of sugar?
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- 3.2015 AMC 10B #5
David, Hikmet, Jack, Marta, Rand, and Todd were in a -person race with other people. Rand finished places ahead of Hikmet. Marta finished place behind Jack. David finished places behind Hikmet. Jack finished places behind Todd. Todd finished place behind Rand. Marta finished in th place. Who finished in th place?
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- 4.2018 AMC 10B #5
How many subsets of contain at least one prime number?
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- 5.2020 AMC 10A #6
How many -digit positive integers (that is, integers between and , inclusive) having only even digits are divisible by
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- 6.2018 AMC 10B #7
In the figure below, congruent semicircles are drawn along a diameter of a large semicircle, with their diameters covering the diameter of the large semicircle with no overlap. Let be the combined area of the small semicircles and be the area of the region inside the large semicircle but outside the small semicircles. The ratio is . What is ?

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- 7.2017 AMC 10A #11
The region consisting of all points in three-dimensional space within units of line segment has volume . What is the length ?
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- 8.2017 AMC 10B #11
At Typico High School, of the students like dancing, and the rest dislike it. Of those who like dancing, say that they like it, and the rest say that they dislike it. Of those who dislike dancing, say that they dislike it, and the rest say that they like it. What fraction of students who say they dislike dancing actually like it?
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- 9.2011 AMC 10A #14
A pair of standard 6-sided fair dice is rolled once. The sum of the numbers rolled determines the diameter of a circle. What is the probability that the numerical value of the area of the circle is less than the numerical value of the circle's circumference?
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- 10.2011 AMC 10A #17
In the eight-term sequence , the value of is 5 and the sum of any three consecutive terms is 30. What is ?
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- 11.2012 AMC 10A #18
The closed curve in the figure is made up of congruent circular arcs each of length , where each of the centers of the corresponding circles is among the vertices of a regular hexagon of side . What is the area enclosed by the curve?

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- 12.2012 AMC 10A #20
A square is partitioned into unit squares. Each unit square is painted either white or black with each color being equally likely, chosen independently and at random. The square is then rotated clockwise about its center, and every white square in a position formerly occupied by a black square is painted black. The colors of all other squares are left unchanged. What is the probability the grid is now entirely black?
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- 13.2013 AMC 10B #20
The number is expressed in the form where and are positive integers and is as small as possible. What is ?
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- 14.2024 AMC 10B #23
The Fibonacci numbers are defined by and for What is
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- 15.2022 AMC 10B #25
Let be a sequence of numbers, where each is either or . For each positive integer , define Suppose for all . What is the value of the sum
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Answers
| # | Answer | Topic and the idea it turns on |
|---|---|---|
| 1 | B | Algebraic Manipulation — Factor 10! out of the numerator: 11! - 10! = 10!(11 - 1), and 10!/9! = 10. |
| 2 | B | Fractions & Decimals — The number of fills is the total amount divided by the cup size: (5/2) divided by (1/4) equals 10. |
| 3 | B | Logic Puzzles — Marta's 6th place anchors a chain: Jack 5th, Todd 3rd, Rand 2nd, then Hikmet is 6 behind Rand in 8th. |
| 4 | D | Basic Counting — Count all 2^8 subsets and subtract the 2^4 subsets built only from the four non-primes 4, 6, 8, 9. |
| 5 | B | Basic Counting — Divisible by 5 with an even last digit forces the units digit to be 0; the thousands digit has 4 even choices and each middle digit 5. |
| 6 | D | Circles — With small radius r the large radius is Nr, so A:B = N : (N^2 - N) = 1 : (N-1), giving N - 1 = 18. |
| 7 | D | Solid Geometry — Points within 3 of a segment form a cylinder of radius 3 capped by two hemispheres, i.e. a cylinder plus one full sphere of radius 3. |
| 8 | D | Ratios, Percents & Averages — With 100 students, 12 like dancing but say they dislike it and 36 dislike it and say so; the requested fraction is 12 out of 48. |
| 9 | B | Basic Probability — Area below circumference means pi d^2/4 < pi d, i.e. d < 4, so the dice sum must be 2 or 3: three of the 36 outcomes. |
| 10 | C | Sequences & Series — Subtracting overlapping triple sums gives A = D = G and B = E = H, so A + H = A + B = 30 - 5. |
| 11 | E | Circles — Each arc has radius 1 and spans 120 degrees; three vertices carry 240-degree outward bulges and three carry 120-degree dents, so hexagon plus 2pi minus pi. |
| 12 | A | Basic Probability — The rotation splits the grid into the center and two 4-cycles; a square stays white only if its predecessor was white, so each 4-cycle needs no adjacent whites. |
| 13 | B | Primes — 2013 = 3*11*61 forces a_1 >= 61; then 61! contains the prime 59, which must be cancelled, so b_1 >= 59, and 61 and 59 work. |
| 14 | B | Sequences & Series — The ratios F_{2n}/F_n are the Lucas numbers 1, 3, 4, 7, 11, ... with the same recurrence, so just add ten small terms. |
| 15 | A | Modular Arithmetic — S_n is the inverse of 7 mod 2^n; because 7 divides 2^{3m} − 1, the bits are 1 then 1,1,0 repeating: x_k = 0 iff 3 divides positive k. |