Practicing Success
The distance between two places A and B is 14 km. A boat travels from A to B downstream and then returns from B to A upstream and takes a total of 3 hours 44 minutes for the entire journey. If the speed of the current is 2 km/h, then what is the speed of the boat, in km/h, in still water? |
$6\frac{1}{2}$ 7 8 $7\frac{1}{2}$ |
8 |
We know that, Time = \(\frac{ Distance }{ Speed }\) Given, = Distance = 14 km Time taken in upstream and downstream = 3 h 44 min Speed of current = 2 km/h Let speed of boat be a km/hr According to the question = \(\frac{ 14 }{ a + 2 }\) + \(\frac{ 14 }{ a - 2 }\) = 3 km/hr + 44 min With the help of options If we put a = 8 \(\frac{ 14 }{ 10 }\) + \(\frac{ 14 }{ 6}\) = 1 hr + 24 min + 2 hr + 20 min = 3 hr + 44 min (satisfied) |