30. A man on tour travels first 160 km at 64 km/hr and the next 160 km at 80 km/hr. The average speed for the first 320 km of the tour is ?

Ans : 71.11 km/hr

Explanation:

Total time taken =		160	+	160	hrs.	=	9	hrs.
		64		80			2

Average speed =		320 x	2	km/hr	= 71.11 km/hr.
			9