GWD 24-36

Kath1985 · 发表于 2010-7-7 09:11:48

36
Marypassed a certain gas station on a highway while traveling west at a constant speed of 50 miles per hour. Then, 15 minutes later, Paul passed the same gas station while traveling west at a constant speed of 60 miles per hour. If both drivers maintained their speeds and both remained on the highway for at least 2 hours, how long after he passed the gas station did Paul catch up with Mary?
A.30 min
B.45 min
C.1 hr
D.1 hr 15 min
E.1 hr 30 min
答案是D

我的解法是
設X小時後Paul走的距離和Mary相同
50X=60(X+15/60)
但是答案卻是負的
1.請問觀念哪邊錯了
2.還有正確解法為何呢

avalon9527 · 发表于 2010-7-7 09:55:49

嗯。。。应该是
50（X+15/60）=60X

Kath1985 · 发表于 2010-7-9 10:53:34

喔我懂了感激

GWD 24-36

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