Question

Solve this problem step by step

Answer 1

Step-by-step explanation:

Let the speed of boat and the speed of current be x and y respectively.

Sailor goes 8 km downstrem in 40 minutes, it means that the boat was moving in the direction of current. So the overall speed of the boat will be sum of speeds of boat and current.

So here speed of boat is x+y

Time taken by boat=40 minutes

Distance covered is 8 km

Applying formula[ time = distance/speed]

40=8/x+y

40(x+y)=8

x+y=1/5 - (1)

When the boat moves back, it moves in opposite direction to the current. It means that overall speed of the boat will be difference of speed of boat and current.

So here speed of the boat = x-y

time taken = 1 hour = 60 minutes

distance covered = 8 km

Applying formula [time = distance/speed]

60=8/(x-y)

60(x-y)=8

x-y= 2/15 - (2)

adding equations (1),(2)

x+y+x-y = 1/5 + 2/15

2x = 5/15

2x = 1/3

x= 1/6 km/minutes

y= 1/5 - x

y = 1/30 km/ minutes

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Answer 2

Step-by-step explanation:

Let the speed of boat and the speed of current be x and y respectively.

Sailor goes 8 km downstrem in 40 minutes, it means that the boat was moving in the direction of current. So the overall speed of the boat will be sum of speeds of boat and current.

So here speed of boat is x+y

Time taken by boat=40 minutes

Distance covered is 8 km

Applying formula[ time = distance/speed]

40=8/x+y

40(x+y)=8

x+y=1/5 - (1)

When the boat moves back, it moves in opposite direction to the current. It means that overall speed of the boat will be difference of speed of boat and current.

So here speed of the boat = x-y

time taken = 1 hour = 60 minutes

distance covered = 8 km

Applying formula [time = distance/speed]

60=8/(x-y)

60(x-y)=8

x-y= 2/15 - (2)

adding equations (1),(2)

x+y+x-y = 1/5 + 2/15

2x = 5/15

2x = 1/3

x= 1/6 km/minutes

y= 1/5 - x

y = 1/30 km/ minutes