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2017/18 AHSMC Part 1

All 16 problems. Take it as a timed test — 1:20:00 on the clock, scored the way the AMC is — or read through the problems and open any of them for its worked solution.

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

  1. Peppa has twice as many apples as pears. After she eats 5050 pears, she now has 44 times as many apples as pears. How many apples does Peppa have?

  2. A math teacher is given a big bag of 300300 candies by a grateful parent. The teacher distributes as many of the candies as possible to her students so that each student gets the same number of candies. There are 1414 candies left over. How many students are there in her class, if each class in the school has at most 3030 students?

  3. A vertical pole is 1212 m from a straight road. Mark is currently on the road 3737 m from the pole.

    Figure for this problem

    How many metres does Mark have to walk on the road before he is 2020 m from the pole?

  4. Some n≥3n \ge 3 different positive real numbers are arranged on a circle such that each number is equal to the product of its two neighbours. The value of nn is

  5. How many pairs (n,p)(n,p) are such that nn is a positive integer, pp is a prime number and n+pnn + \dfrac{p}{n} is a square of a positive integer?

  6. Ben and Cleo can paint a fence in four days. Anna and Ben can do it in two days, Anna and Cleo in three days. How many days, as a fraction, does it take all of them working if Cleo gets injured at the end of the first day and can't come back to work?

  7. The number of ways to walk from (0,0)(0,0) to (20,2)(20,2) by using only up and right unit steps and such that the walk never visits the lines y=xy = x and y=x−18y = x - 18, except at the beginning and end, is

  8. Lan likes red or blue chopsticks, while Dan likes orange or green chopsticks. A drawer in a dark room contains nn chopsticks of each colour, where n>1n > 1 is an integer. Lan goes into the room to get chopsticks for both her and Dan. What is the smallest number of these 4n4n chopsticks that Lan must pick, to be sure that both people will get a matched (i.e. same colour) pair that they like?

  9. Let xx, yy, zz be any real numbers such that 3x+y+2z≥33x + y + 2z \ge 3 and 2y−x+4z≥52y - x + 4z \ge 5. The minimum possible value of 7x+5y+10z7x + 5y + 10z is

  10. In a trapezoid ABCDABCD, with ADAD parallel to BCBC the diagonals intersect at OO. If the area of △AOD\triangle AOD is 916\dfrac{9}{16} of the area of the trapezoid then the ratio of the areas of triangles AODAOD to BOCBOC is equal to

  11. The area of the quadrilateral bounded by the graphs of the functions y=∣x−a∣y = |x - a|, with 0<a<40 < a < 4, and y=2−∣x−2∣y = 2 - |x - 2| is 158\dfrac{15}{8}. The smallest value of aa is

  12. Let aa, bb be positive integers. The number of quadratic equations x2−ax−b=0x^2 - ax - b = 0 having the positive root less than 1010 is

  13. Let SS be a subset of non-negative integers which contains 00, and such that for any number xx in SS, 3x3x and 3x+13x + 1 are also in SS. The least possible number of elements of SS less than 20172017 is

  14. Let aa be a real number so that the equation x4−2ax2−x−a+a2=0x^4 - 2ax^2 - x - a + a^2 = 0 has four different real solutions. Then which of the following must be true?

  15. A positive integer is called a palindrome if it remains unchanged when written backwards. Find the number of 55 digit palindromes which are divisible by 5555.

  16. How many positive integers nn can be found such that the product of all divisors of nn, including nn, is 2424024^{240}?

0 of 16 answered. Each problem left blank still scores 1.5 points.