請教GMATPrep test 2 一道數學Juan買書

teresahan88 · 发表于 2012-4-20 19:55:25

Juan bought some paperback books that cost $8 each and some hardcover books that cost $25 each. If Juan bought more than 10 paperback books, how many hardpaper books did he buy?
1) The total cost of the hardcover books that Juan bought was at least $150
2) The total cost of all the books that Juan bought was less than $260

思路：設paperback數量P，hardcover數量H
1) 25H >=150, 則H>=6, 單獨不充分
2) 8P+25H < 260, 則 25H<260-8P
由題知，P>10,則8P>80,則260-8P<180
則 25H<180, 則 H<7.2，單獨不充分
1)&2), 6<=H<7.2, 則H 為6或7，不充分，選E，但答案為C

請問我的思路哪裏出了問題捏？@@

teresahan88 · 发表于 2012-4-20 20:04:12

幫幫我吧我好像鑽牛角尖了一直出不來><

02021988 · 发表于 2012-4-20 20:46:32

由于P是整数，所以>10本就意味着P>=11，这样8P就>=88，则260-8P<=172，除以25以后不到7本~~

teresahan88 · 发表于 2012-4-20 20:56:27

由于P是整数，所以>10本就意味着P>=11，这样8P就>=88，则260-8P<=172，除以25以后不到7本~~

-- by 会员 02021988 (2012/4/20 20:46:32)

謝謝你>W<

請教GMATPrep test 2 一道數學Juan買書

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