Question

On a 60 km straight road, a bus travels the first 30 km with a uniform speed of 30 kmh-1. How fast must the bus travel the next 30 km so as to have average speed of 40 kmh-1for the entire trip?

Answer 1

Since the distances are equal, you can use the formula,
v = v$v = ( v_{1} + v_{2} )/2$
40= (30 + x)/2
x = 50 kmph