2012_COMPLETE_Chapter_Answer_Key.pdf

MATHCOUNTS

®

2012 Chapter Competition Answer Key The appropriate units (or their abbreviations) are provided in the answer blanks. Answers to the Tiebreaker Tiebreaker Round  problems appear in the Tiebreaker Tiebreaker Round Booklet. Note to coordinators:

National Sponsors Raytheon Company * U.S. Department of Defense *  Northrop Grumman Foundation Foundation *  National Society of Professional Professional Engineers * Bezos Family Foundation * ConocoPhillips * CNA Foundation * Texas Instruments Incorporated * ThinkFun * 3M Foundation

2012 MATHCOUNTS National Competition Sponsor

Founding Sponsors: National Society of Professional Engineers, National Council of Teachers of Mathematics and CNA Foundation Foundation

Copyrightt MATHCOUNTS, Copyrigh MATHCOUNTS, Inc. 2011. 2011. All rights reserved. 02-C12ANS

Sprint Round hours 33 1. _____________ 

30 cents 8. _____________ 

142 14. _____________ 

( 4 , 4 ) 9. _____________ 

1508 cm3 15. _____________  2 2. _____________ 

10 x dollars 3. _____________ 

100 degrees 16. _____________  25 % 10. _____________ 

5 families 4. _____________ 

15 17. _____________  2000 dollars 11. _____________  or 2000.00

6 seconds 18. _____________  12 ounces 5. _____________  6 12. _____________  cm2

6 6. _____________  63 19. _____________  16 13. _____________  cups 20 7. _____________ 

Copyright MATHCOUNTS, MATHCOUNTS, Inc. 2011. 2011. All rights reserved. 2012 Chapter Answer Key

Sprint Round 2 15 20. _____________ 

120 miles 25. _____________ 

−3 26. _____________  140 minutes 21. _____________ 

36 triangles 27. _____________  1 38 22. _____________ 

12 3 units 28. _____________ 

75 units2 23. _____________ 

1 5 29. _____________ 

30 24. _____________ 

3 cm 30. _____________ 

Copyright MATHCOUNTS, MATHCOUNTS, Inc. 2011. 2011. All rights reserved. 2012 Chapter Answer Key

Target Round

1.

$ 33.11 ________________ 

4 3. ________________ 

5  pairs 5. ________________ 

1 6 7. ________________ 

44 integers 6. ________________ 

16 cm2 8. ________________ 

1

1335 minutes 2. ________________ 

4   4. ________________ 

Copyright MATHCOUNTS, MATHCOUNTS, Inc. 2011. 2011. All rights reserved. 2012 Chapter Answer Key

Team Round $ 11,088 or 1. _________________ 

11,088.00

2

units2  s 2 or 7. _________________ 

2  s2

( −4 , 1 ) 2. _________________ 

20 days 8. _________________ 

17 3. _________________ 

1 7 9. _________________ 

3 4. _________________ 

0.51 or .51 10. _________________  $ 10,800 or 5. _________________ 

10,800.00

ft3 18 6. _________________ 

Copyright MATHCOUNTS, MATHCOUNTS, Inc. 2011. 2011. All rights reserved. 2012 Chapter Answer Key

Countdown Round

2 1. _________________ 

2 21. _________________ 

−1 2. _________________ 

4 22. _________________ 

1 9 _________________ 

72π (cm2) 23. _________________ 

−100 4. _________________ 

0 24. _________________ 

20 or 20.00 (dollars) 5. _________________ 

8056 25. _________________ 

6 (mi/h) 6. _________________ 

90 (cm2) 26. _________________ 

72 (hours) 7. _________________ 

87 (points) 27. _________________ 

4 (feet) 8. _________________ 

36 28. _________________ 

6 (bars) 9. _________________ 

32 (cm) 29. _________________ 

27 10. _________________ 

5.5 (miles) 30. _________________ 

140 11. _________________ 

49 31. _________________ 

6 (buckets) 12. _________________ 

5  (in) 32. _________________ 

17 13. _________________ 

6 (skates) 33. _________________ 

11 (years) 14. _________________ 

18 34. _________________ 

4 (lines) 15. _________________ 

36 35. _________________ 

20 (km/h) 16. _________________ 

88 (black beads) 36. _________________ 

3.

11

127 17. _________________ 

36 37. _________________ 

11 (sections) 18. _________________ 

0 38. _________________ 

250 (trees) 19. _________________ 

−3 39. _________________ 

1 (red marbles) 20. _________________ 

4 (percent) 40. _________________ 

Copyright MATHCOUNTS, MATHCOUNTS, Inc. 2011. 2011. All rights reserved. 2012 Chapter Answer Key

Countdown Round

6 41. _________________ 

6 (factors) 61. _________________  1

8 (ways) 42. _________________ 

4 62. _________________ 

4 x 43. _________________ 

50 (minutes) 63. _________________ 

62.5 (percent) 44. _________________ 

38 64. _________________ 

14 (nickels) 45. _________________ 

6 65. _________________ 

20 (units) 46. _________________ 

4 66. _________________ 

-16

1

47. _________________  3

2 67. _________________ 

2 48. _________________ 

121 68. _________________ 

22 49. _________________ 

8 (sides) 69. _________________ 

13 (cm) 50. _________________ 

 x 70. _________________ 

45 (percent) 51. _________________ 

2.5 71. _________________ 

300 52. _________________ 

48 72. _________________ 

11 (units) 53. _________________ 

990 73. _________________ 

5 54. _________________ 

6 74. _________________ 

2 55. _________________ 

75.

6 11 _________________ 

9 56. _________________ 

4 76. _________________ 

40 (percent) 57. _________________ 

5:07 (pm) 77. _________________ 

12 (cm2) 58. _________________ 

162 (in3) 78. _________________ 

−6 59. _________________ 

100 79. _________________ 

72 (degrees) 60. _________________ 

432 (m2) 80. _________________ 

Copyright MATHCOUNTS, MATHCOUNTS, Inc. 2011. 2011. All rights reserved. 2012 Chapter Answer Key