Question

The length and breadth of a playground are 80m and 35m respectively, how long will a boy take to go three times round the field if he walks at rate of 1.5m per second?

Answer 1

length=80m
breadth=35m
perimeter of the field =2(80+35)=230m
distance covered by him=3×230=690m
speed= distance/time
1.5=690/time
time=690/1.5=460seconds

Answer 2

Given that length of a playground l = 80m.

Given that breadth of a playground b = 35m.

Then the perimeter of a playground = 2l + 2b

                                                             = 2 * 80 + 2 * 35

                                                             = 160 + 70

                                                             = 230m.

That means distance covered in one round = 230m.

Given that total distance = 3metres

                                          = 3 * 230

                                          = 690m.


Given that he walks at the rate of 1.5m/s.

We know that speed = Distance/Time.

Therefore the time is taken to cover 3 rounds = 690/1.5

                                                                             = 460 seconds

                                                                             = 7 minutes 40 seconds

                                                     
Hope this helps!