A man riding a bicycle. completes one lap of a square field along its. perimeter at the speed of 39.6 km/hr in 1 minute 20 seconds. What is the area of the held ‘?

To convert km/hr to m/sec multiply the speed with $$\frac{5}{18}$$.
$$39.6 km/hr = \frac{39.6\times 5}{18} = 11 m/sec$$
The man covers the entire distance in 1 minute and 20 seconds which is equal to 80 seconds.
$$Distance=Speed \times Time = 11\times 80 = 880 m$$
The perimeter of the field is 880m.
Length of one side of the field = $$\frac{880}{4} = 220$$ (Since it is a square field.)
Area of the field = $$220^{2} = 48400 sq. mts$$.
Hence Option C is the correct answer.