你由A城去B城, 以50km的平均時速行了1小時.
現在你由原路回去, 但因你趕時間, 你希望將整個旅程的平均時速提升一倍(即由A至B加埋由B回A, 提升一倍: 即平均時速為100km).
問: 你由B城回A城的時速要多快?
數學(邏輯)小遊戲
2012-11-23 11:25 pm
回答 (3)
2012-11-23 11:37 pm
✔ 最佳答案
A 城至 B 城的距離為 50 km, 所以整個旅程為 100 km所以若要整個旅程的平均時速為 100 km/h, 則整個旅程用了的時間需為 1 個小時.
但由於由 A 城至 B 城時已用去了 1 小時, 而回程時必須使用時間 (即使當光速行走), 所以整個旅程用了的時間必超過 1 小時.
所以由 B 城回 A 城時速不論多快都不可能使整個旅程的平均時速為 100 km/h.
參考: 原創答案
2012-11-30 1:30 pm
To the second answerer.
Distance from A to B = 50(1) km = 50km
If speed of return = 150 km/h
-> the time taken for return trip = 50/150 = 1/3 hour
Average speed of the whole journey
= 100km / (1 + 1/3)hour
= 75 km/h
i.e. The answer you provided is the one which should be considered as ridiculous.
Distance from A to B = 50(1) km = 50km
If speed of return = 150 km/h
-> the time taken for return trip = 50/150 = 1/3 hour
Average speed of the whole journey
= 100km / (1 + 1/3)hour
= 75 km/h
i.e. The answer you provided is the one which should be considered as ridiculous.
2012-11-25 4:49 am
150km/h when returning from b to a
from a to b : 50km using 1h
from b to a : 150km using 1h
(50+150)km/(1+1)h
=average speed of 100km per hour( including the trip from a to b, b to a )
2012-11-24 20:50:40 補充：
翻雷滾天 風卷殘雲 's answer is ridiculous
he doesnt understand the question
from a to b : 50km using 1h
from b to a : 150km using 1h
(50+150)km/(1+1)h
=average speed of 100km per hour( including the trip from a to b, b to a )
2012-11-24 20:50:40 補充：
翻雷滾天 風卷殘雲 's answer is ridiculous
he doesnt understand the question
參考: me, me
收錄日期: 2021-04-13 19:07:07
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20121123000051KK00219