A boat traveling with the current, can go 30 miles in 2 hr. The return journey upstream takes 1 hr longer. Find the speed of the boat in still water and find the speed of the current.
2006-12-09 21:19:36 · 4 answers · asked by Boomer0283 2 in Science & Mathematics ➔ Mathematics
Let b = speed of boat in still water,
and c = speed of current.
On the downstream journey, the boat's total speed is b + c.
On the upstream journey, the boat's total speed is b - c.
Using the formula, Distance = Speed * Time,
the downstream formula is : 30 = (b + c) * 2,
while the upstream formula is : 30 = (b - c) * 3
From the 1st formula, we get : b + c = 30 / 2 = 15 mph
From the 2nd formula, we get : b - c = 30 / 3 = 10 mph
Adding the equations gives : 2b = 25, so b = 12.5 mph.
Subtracting the 2nd from the 1st gives : 2c = 5, so c = 2.5 mph.
2006-12-09 21:59:16 · answer #1 · answered by falzoon 7 · 1⤊ 0⤋
20
2006-12-10 05:22:35 · answer #2 · answered by Anonymous · 0⤊ 1⤋
15 mph downstream
10 mph upstream
(10 + 15)/2 = 12.5 mph
2006-12-10 05:23:16 · answer #3 · answered by Steve 2 · 0⤊ 1⤋
well you know i dont know maths soo .blahh.. =]
2006-12-10 05:34:03 · answer #4 · answered by Anonymous · 0⤊ 1⤋