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2013 AMC 10A · #23Circles

In ABC\triangle ABC , AB=86AB = 86 , and AC=97AC=97 . A circle with center AA and radius ABAB intersects BC\overline{BC} at points BB and XX . Moreover BX\overline{BX} and CX\overline{CX} have integer lengths. What is BCBC ?

2013 AMC 10B · #20Primes

The number 20132013 is expressed in the form 2013=a1!a2!am!b1!b2!bn!,2013=\frac{a_1!a_2!\cdots a_m!}{b_1!b_2!\cdots b_n!}, where a1a2ama_1\ge a_2\ge\cdots\ge a_m and b1b2bnb_1\ge b_2\ge\cdots\ge b_n are positive integers and a1+b1a_1+b_1 is as small as possible. What is a1b1|a_1-b_1| ?

2013 AMC 10B · #21Sequences & Series

Two non-decreasing sequences of nonnegative integers have different first terms. Each sequence has the property that each term, beginning with the third, is the sum of the previous two terms, and the seventh term of each sequence is NN . What is the smallest possible value of NN ?

2012 AMC 10A · #25Geometric Probability

Real numbers xx , yy , and zz are chosen independently and at random from the interval [0,n][0,n] for some positive integer nn . The probability that no two of xx , yy , and zz are within 1 unit of each other is greater than 12\frac {1}{2} . What is the smallest possible value of nn ?

2012 AMC 10B · #12Triangles: Area & Pythagorean

Point BB is due east of point AA . Point CC is due north of point BB . The distance between points AA and CC is 10210\sqrt 2 , and BAC=45\angle BAC = 45^\circ . Point DD is 2020 meters due north of point CC . The distance ADAD is between which two integers?

2012 AMC 10B · #15Games & Processes

In a round-robin tournament with 6 teams, each team plays one game against each other team, and each game results in one team winning and one team losing. At the end of the tournament, the teams are ranked by the number of games won. What is the maximum number of teams that could be tied for the most wins at the end of …

2012 AMC 10B · #20Games & Processes

Bernardo and Silvia play the following game. An integer between 0 and 999, inclusive, is selected and given to Bernardo. Whenever Bernardo receives a number, he doubles it and passes the result to Silvia. Whenever Silvia receives a number, she adds 50 to it and passes the result to Bernardo. The winner is the last …

2011 AMC 10A · #2Number Properties

A small bottle of shampoo can hold 35 milliliters of shampoo, whereas a large bottle can hold 500 milliliters of shampoo. Jasmine wants to buy the minimum number of small bottles necessary to completely fill a large bottle. How many bottles must she buy?

2011 AMC 10A · #10Divisibility & Factors

A majority of the 30 students in Ms. Deameanor's class bought pencils at the school bookstore. Each of these students bought the same number of pencils, and this number was greater than 1. The cost of a pencil in cents was greater than the number of pencils each student bought, and the total cost of all the pencils was …

2011 AMC 10B · #10Sequences & Series

Consider the set of numbers {1,10,102,103,,1010}\{1, 10, 10^2, 10^3, \ldots, 10^{10}\} . The ratio of the largest element of the set to the sum of the other ten elements of the set is closest to which integer?

2011 AMC 10B · #24Coordinate Geometry

A lattice point in an xyxy -coordinate system is any point (x,y)(x, y) where both xx and yy are integers. The graph of y=mx+2y = mx +2 passes through no lattice point with 0<x1000 < x \le 100 for all mm such that 1/2<m<a1/2 < m < a . What is the maximum possible value of aa ?

2011 AMC 10B · #25Circles

Let T1T_1 be a triangle with sides 2011,2012,2011, 2012, and 20132013 . For n1n \ge 1 , if Tn=ABCT_n = \triangle ABC and D,E,D, E, and FF are the points of tangency of the incircle of ABC\triangle ABC to the sides AB,BCAB, BC and AC,AC, respectively, then Tn+1T_{n+1} is a triangle with side lengths AD,BE,AD, BE, and CF,CF, if it exists. What is …

2010 AMC 10A · #4Linear Equations & Word Problems

A book that is to be recorded onto compact discs takes 412412 minutes to read aloud. Each disc can hold up to 5656 minutes of reading. Assume that the smallest possible number of discs is used and that each disc contains the same length of reading. How many minutes of reading will each disc contain?

2010 AMC 10A · #8Linear Equations & Word Problems

Tony works 22 hours a day and is paid 0.50perhourforeachfullyearofhisage.DuringasixmonthperiodTonyworked per hour for each full year of his age. During a six month period Tony worked 50daysandearned days and earned 630630 . How old was Tony at the end of the six month period?

2010 AMC 10A · #9Bases & Digits

A palindrome, such as 8343883438 , is a number that remains the same when its digits are reversed. The numbers xx and x+32x+32 are three-digit and four-digit palindromes, respectively. What is the sum of the digits of xx ?

2010 AMC 10A · #16Triangle Centers & Cevians

Nondegenerate ABC{\triangle ABC} has integer side lengths, BD{\overline{BD}} is an angle bisector, AD=3AD = 3 , and DC=8DC=8 . What is the smallest possible value of the perimeter?

2010 AMC 10A · #20Geometric Optimization

A fly trapped inside a cubical box with side length 11 meter decides to relieve its boredom by visiting each corner of the box. It will begin and end in the same corner and visit each of the other corners exactly once. To get from a corner to any other corner, it will either fly or crawl in a straight line. What is …

2010 AMC 10A · #23Conditional Probability & States

Each of 2010 boxes in a line contains a single red marble, and for 1k20101 \le k \le 2010 , the box in the kthk\text{th} position also contains kk white marbles. Isabella begins at the first box and successively draws a single marble at random from each box, in order. She stops when she first draws a red marble. Let P(n)P(n)

2010 AMC 10B · #12Sets, Estimation & Miscellaneous

At the beginning of the school year, 50%50\% of all students in Mr. Wells' math class answered "Yes" to the question "Do you love math", and 50%50\% answered "No." At the end of the school year, 70%70\% answered "Yes" and 30%30\% answered "No." Altogether, x%x\% of the students gave a different answer at the beginning and …

2010 AMC 10B · #15Linear Equations & Word Problems

On a 5050 -question multiple choice math contest, students receive 44 points for a correct answer, 00 points for an answer left blank, and 1-1 point for an incorrect answer. Jesse’s total score on the contest was 9999 . What is the maximum number of questions that Jesse could have answered correctly?

2010 AMC 10B · #17Statistics & Data

Every high school in the city of Euclid sent a team of 33 students to a math contest. Each participant in the contest received a different score. Andrea's score was the median among all students, and hers was the highest score on her team. Andrea's teammates Beth and Carla placed 3737 th and 6464 th, respectively. How …

2010 AMC 10B · #24Sequences & Series

A high school basketball game between the Raiders and Wildcats was tied at the end of the first quarter. The number of points scored by the Raiders in each of the four quarters formed an increasing geometric sequence, and the number of points scored by the Wildcats in each of the four quarters formed an increasing …

2010 AMC 10B · #25Polynomials

Let a>0a > 0 , and let P(x)P(x) be a polynomial with integer coefficients such that P(1)=P(3)=P(5)=P(7)=aP(1) = P(3) = P(5) = P(7) = a , and
P(2)=P(4)=P(6)=P(8)=aP(2) = P(4) = P(6) = P(8) = -a . What is the smallest possible value of aa ?

2009 AMC 10A · #2Number Properties

Four coins are picked out of a piggy bank that contains a collection of pennies, nickels, dimes and quarters. Which of the following could not be the total value of the four coins, in cents?

2009 AMC 10A · #12Triangles: Area & Pythagorean

In quadrilateral ABCDABCD , AB=5AB = 5 , BC=17BC = 17 , CD=5CD = 5 , DA=9DA = 9 , and BDBD is an integer. What is BDBD ?