楼主: soniay

PP一題，尋答

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soniay

楼主

发表于 2006-5-22 22:59:00 | 只看该作者

PP一題，尋答

「題」 A hilker waliking at a constant rate of 4
miles per hour is passed by a cyclist traveling in the same direction
along the same path at a constant rate of 20 miles per hour. THe
cyclist stops to wait for the hiker 5 minutes after passing her, while
the hilker continues to walk at the constant rate. How many minutes
must the cyclist wait until the hilker catches up?

(A)6 2/3

(B)15

(C)20

(D)25

(E)26 2/3

3Q！

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yaoyao99

沙发

发表于 2006-5-23 00:39:00 | 只看该作者

5 minutes = 5/60 hours = 1/12 hours

20(miles/hour) * 1/12 hours = distance cyclist travelled within 5 minutes = 5/3 miles
the time it'll take the hiker to catch up = 5/3 miles / 4(miles/hour) = 5/12 hours = 25 minutes

D