a boy runs around a rectangular ground it's length is thrice it's breadth if the boy covers 2 km in - Maths - Mensuration

Question

a boy runs around a rectangular ground it's length is thrice it's
breadth if the boy covers 2 km in 5 round find the length of the
ground

Shubha · Answer

If Breadth is Bthen Length = 3B
Perimeter of the ground = 2 * (L +B) = 2 * (3B+B) = 8B
In one roud the boy cover a distance equal to perimeter of the
ground
In 5 rounds the boy will cover = 5 * 8B = 40B
It is given that the boy covers a distance of 2 Km or 2000
metre
Therefore 40B = 2000 m
or B= 2000/ 40 = 50Metre
and Length = 3B = 3 * 50 m = 150 m
Length of Ground = 150 metre (ans)

a boy runs around a rectangular ground it's length is thrice it's breadth if the boy covers 2 km in 5 round find the length of the ground