The respective ratio between the speed of a bike, a van and lorry is 3 : 5 : 2. The speed of the van is 250 percent of the speed of the lorry which covers 360 km in 12 hours. What is the average speed of the bike and the van together?

Speed of lorry = $\frac{360}{12}$ = 30 kmph

Speed of van = $\frac{250}{100} x 30$ = 75 kmph

Speed of bike = $\frac{3}{5} x 75$ = 45 kmph

Therefore, now required average speed of bike and van  = $\frac{75 + 45}{2}$= 60 kmph.