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SAT官方每日一题附答案和解析[数学](2018年11月9日)
日期:2018-11-09 09:29

(单词翻译:单击)

每日一题

Mathematics

Black-footed ferrets are the only ferret species native to North America, but they were nearly extinct in the 1970s. Since then, efforts have been made to breed the ferrets in captivity and reintroduce them to the wild. The function f represents the current total population of black-footed ferrets in North America t years after 1991.

f(t)=51.35*1000^(2t/125)

To the nearest year, how many years did (or will) it take for the population to be 10 times larger than it was in 1991?

A.4 years
B.21 years
C.51 years
D.63 years

答案和解析

答案:B

解析:

Choice B is correct. In 1991, t=0 and the equation gives f(0)=51.35. In 2012, t=21 and the equation gives f(21)=523.05 Therefore the population has increased by a factor of approximately 10 after 21 years.

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重点单词
  • extinctadj. 灭绝的,熄灭的,耗尽的
  • populationn. 人口 ,(全体)居民,人数
  • currentn. (水、气、电)流,趋势 adj. 流通的,现在的,
  • approximatelyadv. 近似地,大约
  • ferretn. 白鼬,雪貂,侦探 v. 用雪貂打猎,搜出,驱出
  • equationn. 相等,方程(式), 等式,均衡
  • factorn. 因素,因子 vt. 把 ... 因素包括进去 vi
  • functionn. 功能,函数,职务,重大聚会 vi. 运行,起作用
  • speciesn. (单复同)物种,种类