七年级数学希望杯、华杯赛备考之应用题（下）

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1、七年级数学希望杯、华杯赛备考之应用题（下）一、单选题(共5道，每道20分)1.在浓度为20%的120克盐水溶液中加入（）克盐能得到40%的盐水。A.40 B.80 C.24 D.60 2.有浓度为30%的酒精若干千克，再加入10千克浓度为5%的酒精，混合之后的酒精溶液浓度为20%，问现在的酒精有（）千克。A.35 B.40 C.25 D.50 3.某商品按定价卖出可获利润100元，如果按定价的90%出售，则亏损20元。则商品的购入价是多少元？A.1100元 B.1200元 C.1300元 D.1350元

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