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举手提问....类似题目,来自于prep破解版 1. 86-!-item-!-187;#058&000002 A garden store purchased a number of shovels and a number of rakes. If the cost of each shovel was $14 and the cost of each rake was $9, what was the total cost of the shovels and rakes purchased by the store?
(1) The ratio of the number of shovels to the number of rakes purchased by the store was 2 to 3.
(2) The total number of shovels and rakes purchased by the store was 50. -------------------------------------------------------------------------------------------------------------------------------------------------------- 【答案】C 【思路】 設Qs為shovels的數量 設Qr為rakes的數量 題目問: 14Qs + 9 Qr =? (1) Qs=2a, Qr=3a ,只知比例,不知各為多少,無法求得數量,不充分 (2) Qs + Qr = 50,只知總和,不知各為多少,也無法求數total cost,不充分 (1)+(2) 將(1)代入(2)可得a=10 , 即Qs=20,Qr=30,所以total cost已經可以算出, 充分!
我当时做的时候就是默认整数单位,做出来是B,但是答案是C,到底哪个是正确的? |
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