t = 54mi * 1h/39mi = 1.385 h.
T = 108/52 = 2.077 h for entire distance
2.077 - 1.385 = 0.692 h remaining.
Vavg = 54/0.692 = 78 mi/h.
On a drive from your home to town, you wish to average 52 mph. The distance from your home to town is 108 miles. However, at 54 miles (half way), you find you have averaged only 39 mph.
What average speed must you maintain in the remaining distance in order to have an overall average speed of 52 mph?
Answer in units of mph.
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