Question 465920
{{{3/(1/v[1] + 1/v[2] + 1/v[3]) = 3/((v[2]*v[3] + v[1]*v[3] + v[1]*v[2])/(v[1]v[2]v[3])) = (v[1]v[2]v[3])/(v[2]*v[3] + v[1]*v[3] + v[1]*v[2])}}}
The quantity itself is called the harmonic mean of the rates.

{{{(101*71*106)/(71*106 + 101*106 + 101*71) = 760126/25403 = 29.92}}} mph, to two decimal places.