Question

One man travels 10km upstream in 5 hrs. Another man travels downstream 10km in 3 hrs. If the speed of the stream is 1/2 km/hr, what is the difference in speed of the men?; One man travels 10km upstream in 5 hrs. Another man travels downstream 10km in 3 hrs. If the speed of the stream is 1/2 km/hr, what is the difference in speed of the men?

Answer 1

given,

man1 travels 10km upstream in 5hrs

so upstream speed=10/5=2km/hr.

given man2 travels downstream 10km in 3hrs.

so downstream speed=10/3km/hr.

speed of stream=1/2km/hr.

speed of stream=1/2(downstream speed-upstream speed)

for man1,

1/2=1/2(x-2)(let man1 downstream speed=x)

x=2km/hr.(downstream speed man1)

so speed of man1 in water=1/2(downstream+upstream)

=1/2(2+2)

=2km/hr

for man2,

speed of stream=1/2(10/3-x)

1/2=1/2(10/3-x)

x=10/3(upstream speed)

speed of man2=1/2(10/3+10/3)

=1/2(20/3)

=10/3

diff in sped of men=10/3-2

=4/3

=1.33km/hr