Prep test 中一题求解

victoria620

1. Prep test1 Did it take Pei more than 2 hours walk a distance of 10 miles along a certain trail(1mile =1.6kilometers )

1) Pei walked this distance at an average rate less than 6.4 kilometers per hour
2) On average, it take Pei more than 9 minutes a kilometer to walk this distance.


我选A，答案是D

本人是极其粗心的那种，想大家帮忙看看思路哪里不对。
由1可以得出 v<6.4 s=16 则 t>16/6.4=2.5
由2可以的出 v>1/9*60=20/3 则t<16/(20/3)=2.4 少于2.4小时并不能得出到底是小于两小时还是大于两小时。
则是1可以2不可以。。
哪里错了？？？

victoria620

1. Prep test1 Did it take Pei more than 2 hours walk a distance of 10 miles along a certain trail(1mile =1.6kilometers )

1) Pei walked this distance at an average rate less than 6.4 kilometers per hour
2) On average, it take Pei more than 9 minutes a kilometer to walk this distance.
我选A，答案是D

本人是极其粗心的那种，想大家帮忙看看思路哪里不对。
由1可以得出 v<6.4 s=16 则 t>16/6.4=2.5
由2可以的出 v>1/9*60=20/3 则t<16/(20/3)=2.4 少于2.4小时并不能得出到底是小于两小时还是大于两小时。
则是1可以2不可以。。
哪里错了？？？

-- by 会员 victoria620 (2009/12/21 18:02:16)

有没有回答一下啦~~~~