A body has to travel 120km distance. It travels first 30km with uniform speed 30km/hr. Its average speed is 60 km/hr. What should be its speed in next 90 km distance?

Explanation

Average speed `=("total distance")/("total time")rArr60=(120)/(t)rArrt=2hr`
time taken to cover first 30km `=(30)/(30)=1hr`
time taken to cover next 90km =1hr
So that speed in this duration `=(90)/(1)`=90 km/hr