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2007/08 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. A positive integer has 10011001 digits all of which are 11s. When this number is divided by 10011001, the remainder is

  2. Some cats have got into the pigeon loft because the total head count is 3434 but the total leg count is 8080. The number of cats among the pigeons is

  3. In triangle ABCABC, AB≤1≤BC≤2≤CA≤3AB \le 1 \le BC \le 2 \le CA \le 3. The maximum area of triangle ABCABC is

  4. The number of ways in which five As and six Bs can be arranged in a row which reads the same backwards and forwards is

  5. Among twenty consecutive integers each at least 99, the maximum number of them that can be prime is

  6. The non-negative numbers xx and yy are such that 2x+y=52x + y = 5. The sum of the maximum value of x+yx + y and the minimum value of x+yx + y is

  7. We wish to choose some of the positive integers from 11 to 10001000 inclusive, such that no two differ by 33 or 55. The maximum number of positive integers we can choose is

  8. The number of polynomials pp with integral coefficients such that p(9)=13p(9) = 13 and p(13)=20p(13) = 20 is

  9. In the quadrilateral ABCDABCD, AB=CDAB = CD, AD=2AD = 2 and BC=6BC = 6. ADAD and BCBC are parallel lines at a distance 88 apart. The radius of the smallest circle which can cover ABCDABCD is

  10. The number of pairs (a,b)(a, b) of positive integers such that all three roots of the cubic equation x3−10x2+ax−b=0x^3 - 10x^2 + ax - b = 0 are positive integers is

  11. The real numbers xx and yy are such that x+2y=83x + \dfrac{2}{y} = \dfrac{8}{3} and y+2x=3y + \dfrac{2}{x} = 3. The value of xyxy is

  12. Let θ\theta be an acute angle such that sec⁡2θ+tan⁡2θ=2\sec^2\theta + \tan^2\theta = 2. The value of csc⁡2θ+cot⁡2θ\csc^2\theta + \cot^2\theta is

  13. The diameter ACAC divides a circle into two semicircular arcs. BB is the midpoint of one these arcs, and DD is any point on the other arc. If the area of ABCDABCD is 1616 square centimetres, the distance, in centimetres, from BB to ADAD is

  14. Five students took part in a contest consisting of six true-or-false questions. Student #i\#i gave the answer T to question #j\#j if and only if i<ji < j. The total number of incorrect answers is 88 or 99, and there are more incorrect answers of T than incorrect answers of F. The student who has both an incorrect answer of T and an incorrect answer of F is

  15. An integer nn is randomly chosen from 109910^{99} to 10100−110^{100} - 1 inclusive. The real number mm is defined by m=9n5m = \dfrac{9n}{5}. Of the following five numbers, the one closest to the probability that 1099≤m≤10100−110^{99} \le m \le 10^{100} - 1 is

  16. The smallest value of the real number kk such that (x2+y2+z2)2≤k(x4+y4+z4)(x^2 + y^2 + z^2)^2 \le k(x^4 + y^4 + z^4) holds for all real numbers xx, yy and zz is

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