A fish can swim 45 miles downriver in the same amount of time that it can swim 27 miles upriver.Find the speed?
- GreywolfLv 68 years agoFavorite Answer
x = speed of fish
y = speed of current
effective speed dwon river = x+y
effective speed upriver = x - y
rate * time = distance OR
time = distance / rate
time is the same, so set them equal to each other
45/(x+y) = 27/(x-y)
45 (x-y) = 27 (x+y)
you can play with that, but you will not get an actual answer (only a ratio of x and y since you did not specify the time)
18x = 72y
x = 4y
swim speed is four times the current.
NOTE: the swim speed is the midpoint between the upriver and the down river speed, but the problem does not say the time is an hour, it only says the time is the same.
- DWReadLv 78 years ago
Find the speed of what? the river or the fish in still water?
r = speed of the river current
f = speed of the fish in still water
45/(f + r) = 27/(f - r)
45(f - r) = 27(f + r)
18f = 72r
f = 4r
The fish's speed is 4 times the speed of the current.
- Ian HLv 78 years ago
Because u is the average between (u + v) and (u - v)
(45 + 27)/2 = 36
Regards - Ian