A car traveled 60% of the way from town
A to town B at an average speed of 50
mph. The car travels at an average speed
of "S" mph for the remaining part of the
trip. The average speed for the entire trip
was 45 mph. What is "S"?
.6/50 + .4/x = 1/45
x = 39.13
check. For ease of reading, say the distance is 100 miles
60% is 60 mi
60mi @ 50 mi/hr = 1.2 hr
40mi @ 39.13 mi/hr = 1.022 hr
100mi @ 45mi/hr = 2.222 hr = 1.2 + 1.022