Question 780035
During the first 20 mi of a 50 mi bicycle race, Roger's average speed was 16 mi/h. What must his average speed be during the remainder of the race if he is to finish the race in less than 2.5h? 
----
1st leg DATA::
distance = 20 mi ; rate = 16 mph ; time = d/r = 20/16 = 5/4 hr.
-------
Total journey DATA:
distance = 50 mi ; time = 2.5hr ; rate = 50/2.5 = 20 mph
--------
2nd leg DATA:
distance = 30 mi ; time = (5/2)-(5/4) hr = (5/4) hrs
Equation:
2nd leg rate:
rate = distance/time = 30 mi/(5/4)hr = 120/5 = 24 mph
=================
Cheers,
Stan H.
===========================