A man covers three equal distances first at the rate of 10 km/hr, second at the rate of 20 km/hr, and third at the rate of 30 km/hr. If he covers the third part of the journey in 2 hours. Find the average speed of the whole journey.
1
14.25 km/hr
2
25.25 km/hr
3
16.36 km/hr
4
45.72 km/hr
5
60.50 km/hr