Question

boy playing runs from one end of a ground to the other end at a constant speed of 10 metre per minute and comes back the speed of V if the average speed of the total journey is 12 metre per minute then the value of B is​

Answer 1

Answer:

15m/min

distance covered from one end to other is 'd' then for total is '2d'.

now time taken to go to other end is distance(d) /velocity(10m/min)

and time taken to return is distance(d)/velocity(v)

so now average velocity=total distance/total time taken.

now Vavg=2d/(d/10+d/v)

which is 12=2x10v/(10+v)

so 6=10v/(10+v)

finally we get 4v=60

therefore v=15m/min