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【OG20-P181-229题】
Of the 150 houses in a certain development, 60 percent have air-conditioning, 50 percent have a sunporch, and 30 percent have a swimming pool. If 5 of the houses have all three of these amenities and 5 have none of them, how many of the houses haveexactly two of these amenities?
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分析A选项
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分析B选项
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分析C选项
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分析D选项
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分析E选项
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预约名师一对一题目解析课程题目讨论 （7条评论）
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1289311ww
有且只有2個的分别为 m,n,r(不包括同時有三個的）所求 同時有3個的 x 其他的不包括以上的 y 所以2m+2n+2r+3x+y=90+75+45 又m+n+r+x+y=150-5=145 又x=5 聯立得m+n+r=55
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2019-12-22 18:53:12
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212629sr
为什么（number with all three things）要*2呢？
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2019-12-06 02:34:10
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赤木青帝回复212629sr
同问……看了好久没看懂这个
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2019-12-09 20:54:11
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Stanley想去荷兰回复212629sr
因为中间重合部分被三个圆圈重复计算了3次，所以减掉两次
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2019-12-30 09:03:14
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Thomasgo
Total houses = number with air conditioning + number with sunporch + number with pool - number with only two of the three things - 2(number with all three things) + number with none of the three things 150
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2019-09-20 11:50:54
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EscapeFromFate
Total houses = number with air conditioning + number with sunporch + number with pool - number with only two of the three things - 2(number with all three things) + number with none of the three things 150 = 0.6(150) + 0.5(150) + 0.3(150) - D - 2(5) + 5 150 = 90 + 75 + 45 - D - 10 + 5 150 = 205 - D D = 55
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2019-04-18 23:00:21
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棋王回复EscapeFromFate
很详细，谢谢
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2019-06-25 15:27:37
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贝熊猫
画三个互相交叉起来的圆，所求部分为x，有90+75+45-x-2*5=150-5得x为55
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2019-03-05 22:11:25
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乔治8198
韦恩图公式很重要
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2018-12-12 20:28:22
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hecmelo
air=150*0.6=90 sun=150*0.5=75 swim=150*0.3=45
Total=air+sun+swim-1*two amenities-2*three amenities+none=90+75+45-1*two amenities-10+5=205-two amenities
205-two amenities=150
so two amenities=55
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2017-12-24 00:25:34
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lxra回复hecmelo
请问这是什么公式啊？
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2018-05-15 10:42:45
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