Solve the Problem $$\frac { n } { \sum ( 1 / x ) }$$

Multiple Choice

Solve the problem.
-The harmonic mean is often used as a measure of center for data sets consisting of rates of change, such as speeds. It is found by dividing the number of values (n) by the sum of the reciprocals of all values, expressed as $$\frac { n } { \sum ( 1 / x ) }$$ Pierre drives to work (a distance of 54 miles) at a speed of 74 mph and returns home at a speed of 53 mph. What
Is his average speed for the round trip? Use the harmonic mean.

A) 61.8 mph
B) 63.6 mph
C) 63.5 mph
D) 62.6 mph