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// PAPER // AMC 10A 2017

AMC 10A 2017

2017-02-07

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// PROBLEM 1
// PROBLEM

What is the value of (2(2(2(2(2(2+1)+1)+1)+1)+1)+1)(2(2(2(2(2(2+1)+1)+1)+1)+1)+1)?

// PROBLEM 2
// PROBLEM

Pablo buys popsicles for his friends. The store sells single popsicles for \1each,each,3popsicleboxesfor-popsicle boxes for $2each,andeach, and5popsicleboxesfor-popsicle boxes for $3.WhatisthegreatestnumberofpopsiclesthatPablocanbuywith. What is the greatest number of popsicles that Pablo can buy with $8$?

// PROBLEM 3
// PROBLEM

Tamara has three rows of two 66-feet by 22-feet flower beds in her garden. The beds are separated and also surrounded by 11-foot-wide walkways. What is the total area of the walkways, in square feet?

The garden has 2 columns and 3 rows of flower beds. Each bed is 6 ft wide and 2 ft tall. Beds are separated and surrounded by 1-foot walkways on all sides.

// PROBLEM 4
// PROBLEM

Mia is "helping" her mom pick up 3030 toys that are strewn on the floor. Mia's mom manages to put 33 toys into the toy box every 3030 seconds, but each time immediately after those 3030 seconds have elapsed, Mia takes 22 toys out of the box. How much time, in minutes, will it take Mia and her mom to put all 3030 toys into the box for the first time?

// PROBLEM 5
// PROBLEM

The sum of two nonzero real numbers is 44 times their product. What is the sum of the reciprocals of the two numbers?

// PROBLEM 6
// PROBLEM

Ms. Carroll promised that anyone who got all the multiple choice questions right on the upcoming exam would receive an A on the exam. Which of these statements necessarily follows logically?

// PROBLEM 7
// PROBLEM

Jerry and Silvia wanted to go from the southwest corner of a square field to the northeast corner. Jerry walked due east and then due north to reach the goal, but Silvia headed northeast and reached the goal walking in a straight line. Which of the following is closest to how much shorter Silvia's trip was, compared to Jerry's trip?

// PROBLEM 8
// PROBLEM

At a gathering of 3030 people, there are 2020 people who all know each other and 1010 people who know no one. People who know each other hug, and people who do not know each other shake hands. How many handshakes occur?

// PROBLEM 9
// PROBLEM

Minnie rides on a flat road at 2020 kilometers per hour (kph), downhill at 3030 kph, and uphill at 55 kph. Penny rides on a flat road at 3030 kph, downhill at 4040 kph, and uphill at 1010 kph. Minnie goes from town AA to town BB, a distance of 1010 km all uphill, then from town BB to town CC, a distance of 1515 km all downhill, and then back to town AA, a distance of 2020 km on the flat. Penny goes the other way around using the same route. How many more minutes does it take Minnie to complete the 4545-km ride than it takes Penny?

// PROBLEM 10
// PROBLEM

Joy has 3030 thin rods, one each of every integer length from 11 cm through 3030 cm. She places the rods with lengths 33 cm, 77 cm, and 1515 cm on a table. She then wants to choose a fourth rod that she can put with these three to form a quadrilateral with positive area. How many of the remaining rods can she choose as the fourth rod?

// PROBLEM 11
// PROBLEM

The region consisting of all points in three-dimensional space within 33 units of line segment AB\overline{AB} has volume 216π216\pi. What is the length ABAB?

// PROBLEM 12
// PROBLEM

Let SS be a set of points (x,y)(x,y) in the coordinate plane such that two of the three quantities 3, x+2,3,~x+2, and y4y-4 are equal and the third of the three quantities is no greater than this common value. Which of the following is a correct description for SS?

// PROBLEM 13
// PROBLEM

Define a sequence recursively by F0=0, F1=1,F_{0}=0,~F_{1}=1, and Fn=F_{n}= the remainder when Fn1+Fn2F_{n-1}+F_{n-2} is divided by 3,3, for all n2.n\geq 2. Thus the sequence starts 0,1,1,2,0,2,0,1,1,2,0,2,\ldots What is F2017+F2018+F2019+F2020+F2021+F2022+F2023+F2024?F_{2017}+F_{2018}+F_{2019}+F_{2020}+F_{2021}+F_{2022}+F_{2023}+F_{2024}?

// PROBLEM 14
// PROBLEM

Every week Roger pays for a movie ticket and a soda out of his allowance. Last week, Roger's allowance was AA dollars. The cost of his movie ticket was 20%20\% of the difference between AA and the cost of his soda, while the cost of his soda was 5%5\% of the difference between AA and the cost of his movie ticket. To the nearest whole percent, what fraction of AA did Roger pay for his movie ticket and soda?

// PROBLEM 15
// PROBLEM

Chloé chooses a real number uniformly at random from the interval [0,2017][0, 2017]. Independently, Laurent chooses a real number uniformly at random from the interval [0,4034][0, 4034]. What is the probability that Laurent's number is greater than Chloé's number?

// PROBLEM 16
// PROBLEM

There are 10 horses, named Horse 1, Horse 2, \ldots, Horse 10. They get their names from how many minutes it takes them to run one lap around a circular race track: Horse kk runs one lap in exactly kk minutes. At time 0 all the horses are together at the starting point on the track. The horses start running in the same direction, and they keep running around the circular track at their constant speeds. The least time S>0S>0, in minutes, at which all 10 horses will again simultaneously be at the starting point is S=2520S=2520. Let T>0T>0 be the least time, in minutes, such that at least 5 of the horses are again at the starting point. What is the sum of the digits of TT?

// PROBLEM 17
// PROBLEM

Distinct points PP, QQ, RR, SS lie on the circle x2+y2=25x^2+y^2=25 and have integer coordinates. The distances PQPQ and RSRS are irrational numbers. What is the greatest possible value of the ratio PQRS\dfrac{PQ}{RS}?

// PROBLEM 18
// PROBLEM

Amelia has a coin that lands heads with probability 13\tfrac{1}{3}, and Blaine has a coin that lands on heads with probability 25\tfrac{2}{5}. Amelia and Blaine alternately toss their coins until someone gets a head; the first one to get a head wins. All coin tosses are independent. Amelia goes first. The probability that Amelia wins is pq\tfrac{p}{q}, where pp and qq are relatively prime positive integers. What is qpq-p?

// PROBLEM 19
// PROBLEM

Alice refuses to sit next to either Bob or Carla. Derek refuses to sit next to Eric. How many ways are there for the five of them to sit in a row of 5 chairs under these conditions?

// PROBLEM 20
// PROBLEM

Let S(n)S(n) equal the sum of the digits of positive integer nn. For example, S(1507)=13S(1507) = 13. For a particular positive integer nn, S(n)=1274S(n) = 1274. Which of the following could be the value of S(n+1)S(n+1)?

// PROBLEM 21
// PROBLEM

A square with side length xx is inscribed in a right triangle with sides of length 33, 44, and 55 so that one vertex of the square coincides with the right-angle vertex of the triangle. A square with side length yy is inscribed in another right triangle with sides of length 33, 44, and 55 so that one side of the square lies on the hypotenuse of the triangle. What is xy\tfrac{x}{y}?

// PROBLEM 22
// PROBLEM

Sides AB\overline{AB} and AC\overline{AC} of equilateral triangle ABCABC are tangent to a circle at points BB and CC respectively. What fraction of the area of ABC\triangle ABC lies outside the circle?

// PROBLEM 23
// PROBLEM

How many triangles with positive area have all their vertices at points (i,j)(i,j) in the coordinate plane, where ii and jj are integers between 11 and 55, inclusive?

// PROBLEM 24
// PROBLEM

For certain real numbers aa, bb, and cc, the polynomial g(x)=x3+ax2+x+10g(x) = x^3 + ax^2 + x + 10 has three distinct roots, and each root of g(x)g(x) is also a root of the polynomial f(x)=x4+x3+bx2+100x+c.f(x) = x^4 + x^3 + bx^2 + 100x + c. What is f(1)f(1)?

// PROBLEM 25
// PROBLEM

How many integers between 100100 and 999999, inclusive, have the property that some permutation of its digits is a multiple of 1111 between 100100 and 999?999? For example, both 121121 and 211211 have this property.