The time taken by a boat to travel 13 km downstream is the same as time taken by it to travel 7 km upstream. If the speed of the stream is 3 km/h, then how much time (in hours) will it take to travel a distance of 44.8 km in still water?
Answer & explanation
Correct answer: option 1
Speed of the stream = 3 km/hr
Let speed of the boat be y km/hr
Time = \(\frac{ Distance }{ Speed }\)
According to the question
\(\frac{ 13}{ (y + 3) }\) = \(\frac{ 7}{ (y - 3) }\)
= 13 (y – 3) = 7 (y + 3)
= 13y – 39 = 7y + 21
= 13y – 7y = 21 + 39
= 6y = 60
= y = 10
So, speed of boat = 10 km/hr
Time taken to cover 44.8 km distance in still water = \(\frac{ 44.8}{ (10) }\) = $4 \frac{12}{25}$