Question

A boat travels 4km in 10 minutes with the current and 1km in 15 minutes against the current find speed of boat​

Answer 1

Answer:

700/3 m/s

Step-by-step explanation:

4km = 4000 m

Let speed of boat is x and speed of stream is y

Speed with current = Distance / time

Speed with current = 4000/10

= 400 m/s

ATQ,

x + y = 400 m/s   (equation 1)

Now,

1 km = 1000 m

speed against current= distance / time

speed against current= 1000/15

= 200/3    m/s

ATQ,

x - y = 200/3 (equation 2)

Adding equation 1 and 2

we get

2x = 400 + 200/3

2x = $\frac{1200+200}{3} \\\\1400/3$

x = 700/3 meter per second

speed of boat  = 700/3 m/s

Answer 2

Answer:

3 hours

Step-by-step explanation:

Keep in mind that a is a symbol for the speed of the boat in still or stationary water, b for the speed of the boat in the water current, where water is moving in the same direction of the boat, e for the speed of the boat when moving in water, where water is moving in the opposite direction of the boat’s, c for the speed of water current, d for distance and t for time.

e=4km/hr=0.0668km/min

b=1km/min

e=a−c=0.0668km/min

b=a+c=1km/min

b+e=a+a−c+c=2a=1+0.668=1.0668

a=0.0834km/min

t=da=15/0.0834≈180minutes=3hours