Question

a man walk at 1 per second for 60 minute you take rest for 20 minutes and then walk for with a speed of 1 metre per second for 60 minutes find its average speed

Answer 1

 Total Distance = 1 × 3600 + 1 × 3600
                            = 7200 metersTotal Time = 120 x 60 + 20 x 60 minutes
Average Speed = Total Distance / Total Time                              = 7200/8400                              = 6/7 m/s
this is the required Average Speed

Answer 2

Hello Dear.

Here is the answer---

Given---

Distance covered by the man in 1 second. = 1 m.
∴ Distance covered by the man in 60 min.= 1 × 60 × 60
  = 3600 m.
Now,
Distance covered by the man is the 20 min. = 0 m.
[Since boy is taking the rest]

Distance covered by the man in last 60 min. = 1 m × 60 × 60
= 3600 m.

∴ Total Distance Covered by the man = 3600 + 0 + 3600
  = 7200 m.

Total Time taken by the man = 60 min. + 20 min. + 60 min.
 = 140 min.
 = 140 × 60 seconds.
 = 8400 seconds.


Now,
∵ Average Speed = Total Distance/Total Time
   = 7200/8400
   = 72/84
   = 6/7 m/s.

∴ Average Speed of the man during the entire Journey is 6/7 m/s.


Hope it helps.