2013美国数学竞赛AMC8题目及答案.doc

2013 AMC 8 Problems/Problem 1
Probfem
Dani 匸目 wants to arra nge her model 匸 are m raws we th exa 匸 tly 6 cars in each , the second jump is 2 meters, the third jump is 4 meters, and so on, then on which jump will he first be able to jump more tha n 1 kilometer?
(A) 9th (B) 10th (C) 1 严 (D) 12th (E) 13th
What is the ratio of the least com mon multiple of 180 and 594 to the greatest com mon factor of 180 and 594?
(A) 110 (B) lfiS (C) 330 (D) 625 (E) 660
Ted's gran dfather used his treadmill on 3 days this week. He went 2 miles each day. On Mon day he jogged at a speed of 5 miles per hour. He walked at the rate of 3 miles per hour on Wedn esday and at 4 miles per hour on Friday. If Grandfather had always walked at 4 miles per hour, he would have spent less time on the treadmill. How many minutes less?
1(A) 1 (B)2 (C)3 (D) 4 (E)5
At the 2013 Winn ebago County Fair a ven dor is offeri ng a "fair special" on san dals. If you buy one pair of sandals at the regular price of $50, you get a second pair at a 40% discount, and a third pair at half the regular price. Javier took adva ntage of the "fair special" to buy three pairs of san dals. What perce ntage of the $150 regular price did he save?
|(A) 25 (B) 30 (C) 33 (D) 40 {E) 45
When Clara totaled her scores, she inadvertently reversed the units digit and the tens digit of one score. By which of the follow ing might her in correct sum have differed from the correct one?
(A) 45 (B) 46 (C) 47 (D) 48 (E) 49
Let the two digits be 4and 2
The correct score was
:L亠二 Clara misinterpreted it as
10b + a .The differe nee betwee n the two is
19a — 9fr|
which factors into
|9(。一 b)|
.Therefore, since the differe nee is a multiple of 9, the only an swer
(A) 45
16
40
55
79
choice that is a multiple of 9 is
If 沪一沪一皙：f - ,and 5? + 6* = 1421 ,what is the product of 戸，r , and s ?
(A) 27 (B) 40 (C) 50 (D) 70 <E) 90
A n umber of stude nts from Fib on acci Middle School are tak ing part in a commu nity service