A man riding a bicycle , completed one lap of a circular field along its circumference at the speed of 79.2 km/hr in 2 minutes 40 seconds . What is the area of the field ?

Options

A. 985600 sq metre
B. 848500 sq metre
C. 795600 sq metre
D. Cannot be determined

Answer

A

Explanation

79.2 km/hr = `79.2 xx (5)/(18) = 22` m/s
2 min 40 sec = `2 xx 60 + 40 = 120 + 40 = 160` sec .
Circumference of circular field = speed `xx` time
`22 xx 160 = 3520` m
Radius of circular field (r) = `("circumference")/(2pi)`
`(3520 xx 7)/(2 xx 2) = 560` m
Area of circular field = `pi r^(2) = (22)/(7) xx (560)^(2)`
`= (22)/(7) xx 560 xx 560`
`= 985600 m^(2)`