IIMB 2001 (QA) PYQs

Nidhi reached her institute in 3 hours while travelling by bus with a wheel radius of 70 cm and making 250 revolutions in one minute. One day, she left for the institute one hour later than usual time. Then to reach her institute on time, she should increase her speed by ____. [Use $\pi = \frac{22}{7}$]

A car travels the first $160$ km at a speed of $64$ km/hr and the next $160$ km at a speed of $80$ km/hr . What is the average speed for the first $320$ km of the tour ?

The time taken by a boat to cover a certain distance in still water is 20% less than the time it takes to cover the same distance upstream. The speed of the stream is 4.5 km/h. How much total time (in hours) will the boat take to cover 60 km downstream and 30 km upstream?