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put this solution on YOUR website!A man in a speed boat which could only travel at 50km/h was driving his boat up a river which flowed with a constant speed(S SAY).
RELATIVE SPEED WHILE TRAVELLING UPSTREAM = 50-S KMPH
As he was driving his spare life jacket fell of the boat (AT P SAY), 20 minutes
DISTANCE TRAVELLED BY MAN IN 20 MTS=1/3 HR.UP STREAM = (50-S)/3 KM =PQ SAY
DISTANCE TRAVELLED BY JACKET IN 20 MTS DOWN STREAM = S/3 KM =PR SAY
HENCE INTIAL DISTANCE OF SEPERATION= D =PQ+PR= S/3 + (50-S)/3 = 50/3 KM.
later the man noticed the jacket was gone and turned back to get it.
TIME TAKEN TO GET IT = D / RELATIVE SPEED TRAVELLING DOWN STREAM BETWEEN MAN AND JACKET = D/(50+S-S)=D/50
=50/(3*50) =1/3 HRS.
DISTANCE TRAVELLED BY HIM IN THIS TIME = QT = (50+S)/3
He found it 3km away from where he lost it.
PT=3 KM = QT-PQ = [(50+S)/3]-[(50-S)/3]
50+S-50+S=3*3=9
2S=9
S=4.5 KMPH
How fast was the river flowing?
