If the velocity of the object changes from 4 cm / sec to 14 cm / sec in 9 seconds, then at what average rate is the velocity changing?

Starting from rest, a ball rolls down a constant incline.  It requires 9.900001 seconds to roll the 94 centimeter length of the incline.

An object which accelerates uniformly from rest will attain a final velocity which is double its average velocity.

In 12 seconds, a bicycle accelerating uniformly from rest covers a distance of 175 meters.  At what average rate is its velocity changing?