Question

A rectangular field is 90m by 70m. A man walks around it at the rate of 4 km per hour. What time will he take in 5 rounds.

Explanation needed ​

Answer 1

Perimeter of the rectangle is 90 + 90 + 70 +70 = 160 + 160 =320 m

In km we have 320/ 1000 = 0.320 km because 1000m = 1 km

So his speed = 4 km / hr = 4 km / 60 min = 1 km in 15 min .

5 rounds implies 5 ( 0.320 ) = 1.6 km

So if 1 km is 15 min then 1.6 km  

15 × 1.6 min = 24 min

Hence the person takes 24 min .