2017年4月11日STA官方每日一题---数学选择.

　　为了让我们更好的适应sat考试，sat官网每天都会有sat官方每日一题，下面是小编为您整理的2016年4月sat官方每日一题，是数学选择，让我们一起来看一看这道数学选择吧。

　　Read the following SAT test question and then click on a button to select your answer.

　　The time it takes Erica to run one mile decreased consistently throughout her track season. She estimates that her time to run a one-minute mile decreased by about 15 seconds for every 2 weeks into the season. If Erika ran one mile in 500 seconds at the start of the season, and x weeks after the start of the season ran one mile in 425 seconds, which of the following equations best represents this context?

　　A. 500-7.5x=425

　　B. 500-15x=425

　　C. 500+7.5x=425

　　D. 500+15x=425

　　答案：A

　　解析：

　　Choice A is correct. The time it took Erica to run one mile decreased by about 15 seconds for every 2 weeks of the season. This is equivalent to a decrease of 7.5 seconds every week.

　　If Erika trains for x weeks, 7.5x represents the total time, in seconds, that she has shaved off the time it took her to run one mile.

　　Subtracting this from her starting time gives the approximate time (in seconds) it takes her to run one mile at week x.

　　500-7.5x

　　Since it takes her 7 minutes and 5 seconds, or 425 seconds to run a mile after x weeks of the season, we can create the following equation:

　　500-7.5x=425

　　The equation that best represents the context is 500-7.5x=425.

　　上面是小编为您整理的2016年4月sat官方每日一题，是数学选择题，为了让我们更好的适应sat考试，sat官网每天都会发布sat官方每日一题，让我们一起来看一看这道数学选择吧。

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