Rohan travels the first 100 km by car at the speed of 25 km/hr, travels another 150 km by bike at the speed of 75 km/hr, travels 600 km by aeroplane at the speed of 150 km/hr and Rohan covers the remaining 20 km of distance with the speed of 2.5 km/hr. Find the average speed of Rohan.
1
\(20\) km/hr
2
\(\frac{870}{18}\) km/hr
3
\(\frac{870}{16}\) km/hr
4
25 km/hr