The speed of a boat in still water is 8 km/hr. If it takes the same time in going 20 km downstream as it takes in going 12 km upstream. Find the speed of the water of the river.
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Answered by
8
Speed of boat = 8 km/hr
Let speed of water be 'y'
Upstream speed = 8 - y
Downstream speed = 8 + y
Given, Time taken to go 20 km downstream = Time taken for 12 km upstream
20/8+y = 12/8-y
5/8+y = 3/8-y
5*(8-y) = 3*(8+y)
40 - 5y = 24 + 3y
8y = 16
y = 2
Hence speed of water of river = 2 km/hr
Hope it helps.
Let speed of water be 'y'
Upstream speed = 8 - y
Downstream speed = 8 + y
Given, Time taken to go 20 km downstream = Time taken for 12 km upstream
20/8+y = 12/8-y
5/8+y = 3/8-y
5*(8-y) = 3*(8+y)
40 - 5y = 24 + 3y
8y = 16
y = 2
Hence speed of water of river = 2 km/hr
Hope it helps.
Answered by
0
Let the speed of the stream be x km\hr.
The speed of the boat upstream = (18 - x) km/hr
The speed of the boat downstream = (18 + x) km/hr
Distance = 24 km
As given in the question,
Time for upstream = 1 + Time for downstream
24/(18 - x) = 1 + 24/(18 + x)
24/(18 - x) - 24/(18 + x) = 1
x2 + 48x - 324 = 0
(x + 54)(x - 6) = 0
x ≠ - 54 as speed cannot be negative.
x = 6
The speed of the stream = 6 km/hr
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