A certain bridge is 4,024 feet long. Approximately how many minutes does it take to cross this bridge at a constant speed of 20 miles per hour? (1 mile = 5,280 feet)


1

2

4

6

7

加入错题本 分享
纠错
考题讲解

题目分析：

~$4024 feet=\frac{4024}{5280} mile$~所求的时间~$t=\frac{4024}{5280}/20=\frac{4024}{5280*20} h$~

所求的时间为minutes=~$\frac{4024}{5280*20} *60=\frac{4024*3}{5280}=\frac{4024}{1760}=2\frac{504}{1760}≈2.2h≈2h$~

综上：答案就是B

展开显示

~$4024ft =\frac{4024}{5280} mile$~
~$\frac{4024}{5280} /20=\frac{4024}{(5280)(20)}h$~
~$\frac{4024}{(5280)(20)}×60min≈\frac{4000}{5000}×\frac{60}{20}≈2min$~

展开显示

登录 或 注册 后可以参加讨论

查看全部2条讨论
OG2017Q-PS
考点
知识点