Question

17. The speed of a stream is 2 km/h. A boat travels
between two ports downstream in 4 hours and
upstream in 6 hours. Find the speed of the boat and
also the distance covered.​

Answer 1

Step-by-step explanation:

let the speed of the boat be x and distance be s

speed in downstream = x + 2

speed in upstream = x - 2

now,

(x+2)*4 =s...... ep 1 ( speed × time = distance)

( x-2) × 6 = s........ eq 2

solving both equations we get

x = 10 , y = 48

therefore speed of boat is 10 km/h and distance is 48 km

Answer 2

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 = 6(x−2)km....(ii)

From Equation (i) and (ii)

4(x+2) = 6(x−2)

4x+8 = 6x−10

x = 9

∴ Distance between two ports =4(x+2)

=4(9+2)km = 44km

Speed of the boat:

Time = (4+6)hours = 10hours

Distance = 44km

∴ Speed = Distance

Time

= 44km

10hr

= 4.4km/hr