『艾蕾特教育』AMC8 -- 2006年真题解析( 三 )


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Answer: A
Solution:
x=6*q1+4; => x+2=6*(q1+1);x=5*q2+3; =>x+2=5*(q2+1);If there were two more coins in the box, the number of coins would be divisible by both 6 and 5. The smallest number that is divisible by 6 and 5 is 30, so the smallest possible number of coins in the box is 28 and the remainder when divided by 7 is 0.Problem 24『艾蕾特教育』AMC8 -- 2006年真题解析
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Answer: A
【『艾蕾特教育』AMC8 -- 2006年真题解析】Solution:
CD*101=CDCD. So ABA=101, A=1,b=0. A+B=1.Problem 25
『艾蕾特教育』AMC8 -- 2006年真题解析
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Answer: B
Solution:
Notice that 44 and 38 are both even, while 59 is odd. If any odd prime is added to 59, an even number will be obtained. However, the only way to obtain this even number would be to add another even number to 44, and a different one to 38. Since there is only one even prime (2), the middle card's hidden number cannot be an odd prime, and so must be even. Therefore, the middle card's hidden number must be 2, so the constant sum is 59+2=61. Thus, the first card's hidden number is 61-44=17, and the last card's hidden number is 61-38=23. Since the sum of the hidden primes is 2+17+23=42. the average of the primes is 42/3=14.AMC培训、答疑 , 请联系微信 / 电话:136 1118 1627
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