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1. A ship sails to and from Island A and B which are 48 km apart. The speed of the boat in still water is v km/h and the speed of the water current is x km/h. The upsteam voyage takes 4 hours and the downstream voyage takes 3 hours. What are the values of v and x?
Answer: v= -------------, x=----------------
maths! maths! maths!
2009-07-18 1:19 am
回答 (1)
2009-07-18 1:29 am
✔ 最佳答案
Downstream speed = (v + x) km/h, since distance = 48so time = distance/speed = 48/(v + x) = 3
or v + x = 48/3 = 16.............(1)
Upstream speed = (v - x) km/h and time taken = 4 hr.
so v - x = 48/4 = 12............(2)
(1) + (2) we get 2v = 28
v = 14 km/h.
so x = 16 - v = 16 - 14 = 2 km/h.
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