The length of a rectangular field is twice it's breadth. A girl jogged around it 4 times and covered a distance of 4.5 km. What is the length of the field?
The distance cover in 4 laps is 4.5 km, So one lap is 4.5/4 = 1.125 km.
Let the breadth of the field be B so the length will be L or 2B.
The perimeter of the field is 2L+2B or 4B+2B = 6B = 1.125, so B = 1.125/6 = 0.1875 km and the length is 2*0.1875 = 0.375 km.
Check: perimeter = 2*0.375 + 2*0.1875 = 1.125 km and 4 laps covers 4*1.125 = 4.5 km. correct.
