2015年6月12日SAT官方逐日一題
標題範例:Mathematics > Standard Multiple Choice
Read the following SAT test question and then click on a button to select your answer.
A geologist has 10 rocks of equal weight. If 6 rocks and a 10-ounce weight balance on a scale with 4 rocks and a 22-ounce weight, what is the weight, in ounces, of one of these rocks?
(A) 4
(B) 5
(C) 6
(D) 7
(E) 8
謎底:C
【剖析】
Let r equal the weight of each rock, in ounces. The weight on one side of the scale is 6r+10 ounces and the weight on the other side is 4r+22 ounces. Since the two weights balance, you can write the equation 6r+10 =4r+22. Solving this equation yields r=6.
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