A motorboat whose speed in still water is 18 km/h, takes 1 hour more to go 24 km upstream than to return downstream to the same spot. Find the speed of the stream.
Answers
Given parameters:
The speed of the motorboat in still water =18 kmph
Let us consider
The speed of the stream = s
Speed of boat upstream = Speed of a boat in still water – the speed of a stream
Speed of boat upstream = 18 – s
Speed of boat downstream = Speed of a boat in still water + speed of a stream
Speed of boat downstream = 18 + s
Time is taken for upstream = Time taken to cover downstream + 1
time =distance/speed
DistanceupstreamSpeedupstream=DistancedownstreamSpeeddownstream+1
24/ (18 – s) = [24/(18 + s)] + 1
24(18+s) = 24(18−s) + (18−s)(18+s)
s2 + 48s − 324 = 0
s2 + 54s − 6s − 324 = 0
(s+54)(s−6) = 0
s = 6,−54 but
s ≠−54
Since the speed of steam cannot be negative.
∴ s = 6km/hr
Given parameters:
The speed of the motorboat in still water =18 kmph
Let us consider
The speed of the stream = s
Speed of boat upstream = Speed of a boat in still water – the speed of a stream
Speed of boat upstream = 18 – s
Speed of boat downstream = Speed of a boat in still water + speed of a stream
Speed of boat downstream = 18 + s
Time is taken for upstream = Time taken to cover downstream + 1
time =distance/speed
Distance upstream/Speed upstream=Distanced Own Stream/Speed downstream
24/ (18 – s) = [24/(18 + s)] + 1
24(18+s) = 24(18−s) + (18−s)(18+s)
s2 + 48s − 324 = 0
s2 + 54s − 6s − 324 = 0
(s+54)(s−6) = 0
s = 6,−54 but
s ≠−54
Since the speed of steam cannot be negative.
∴ s = 6km/hr