P. 4617. A student went by bicycle to Saddle City from Frame Village. He planned to go with an average speed of 18 km/h. Because of the heavy traffic, in the first third of his journey his average speed was only 15 km/h.
a) What should his average speed be in the remaining part of his journey, if he is to arrive at the planned time?
b) What should his average speed be in the remaining time, if his speed was 15 km/h in the first one-third of the time of his journey?
Deadline expired on 10 April 2014.