<p>@meumeu Definitely not! In a “Xiggi” problem you are given the averages for half the trip - and each half is generally different. Harmonic means do not behave like arithmetic means! If you half a distance you get half the distance travelled. If you half a time you get half the time it took. If you half the rate you get a meaningless number. </p>
<p>For example, if you were traveling 30 mph and then 60 mph, then Xiggi’s formula gives an average rate of 40 mph for the whole trip. Half of 40 is 20. This number means nothing! You were always travelling faster then 20mph.</p>