Question

The area of rectangular field is 3584m. sq and its length is 64m. A boy runs around the field at the rate of 6km/h. How long will he take to go 5 times around it ?

Answer 1

3584= 64 × width
width = 56
perimeter of rectangle is =2(l+w)
....…...........= 2(64+56)=240 m
1 round = 240
5 times = 240× 5= 1200m or 1.2 km
then time taken = distance/ speed
.................=1.2/6=0.2 h

Answer 2

We know that Area = length * breadth

Then breadth = Area/Length

                      = 3584/64

                      = 56m.

We know that perimeter of the field = 2(l + b)
                
                                                             = 2(64 + 56)

                                                            = 240m.


If the distance covered in 1 time = 240m

Then the distance covered in 5 times = 240 * 5 = 1200

Given speed = 6km/hr

                      = 6 * 5/18

                     = 5/3 m/s.


We know that Time = Distance/Speed

                                 = 1200/5/3

                                 = 720 seconds.


Hope this helps! :)