Sandeep goes Rawatsar to Hanumangarh but he cannot walk the same speed continuously. So, he covers 20 km by speed of 5 km/hr, 12 km by speed of 4 km/hr, and 8 km by speed of 2 km/hr. Find the average speed of Sandeep.
1
2 km/hr
2
1.5 km/hr
3
40/11km/hr
4
20/7 km/hr
5
None of these