Question

A streamer goes downstream from one port to another in 4 hours. It covers the same distance upstream in 5 hours. If the speed of the stream is 2 km/h, the distance between the two ports is

विकल्प

• 80 km

• 81 km

• 70 km

• 71 km

Answer 1

80 km
Explanation:
Let speed of the streamer in still water = x km/hr

Speed of downstream = (x + 2) km/hr

Distance between the ports = 4(x + 2) km ........ (i)

Speed of upstream = (x – 2) km/hr

Distance between the ports = 5(x – 2) km ........ (ii)

from Equation (i) and (ii)

4 (x + 2) = 5 (x – 2)

4x + 8 = 5x – 10

x = 18

∴ Distance between two ports = 4 (x + 2)

= 4 (18 + 2) km = 80 km