the speed of a boat in still water is 18 km/hr.It can go 48km upstream and return to the original point in 6 hours find the speed

1 thought on “the speed of a boat in still water is 18 km/hr.It can go 48km upstream and return to the original point in 6 hours find the speed”

1. Given:

   Speed of boat in still water = 18km/hr

   Let speed of the stream = s

   Speed of boat upstream = Speed of boat in still water – speed of stream = 18−s

   Speed of boat down stream = Speed of boat in still water + speed of stream = 18+s

   Time taken for upstream = Time taken to cover downstream + 1

   ⇒SpeedupstreamDistanceupstream=SpeeddownstreamDistancedownstream+1

   ⇒18−s24=18+s24+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

   ⇒s=−54

   Thus, s=6km/hr, Speed of steam cannot be negative.

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