Question: Rani’s Average Speed

Comment on Rani’s Average Speed

I actually solved this algebraically using formulas and it worked. Amazing.

Why the weighted average doesn't work here?
Full Distance = X + Y

[X/(X + Y)]*A + [Y/(X + Y)]*B

(XA + YB)/(X + Y)

Answer D?
greenlight-admin's picture

Great question!
I'm not 100% sure, but I believe it has something to do with the fact that Weighted Averages are typically used to find an average measurement among a population of measurements (e.g, the average height among a population of males and females).
When we calculate average speed we aren't calculating an average of a number of values.
This is my initial hunch. If I think of a better response I,ll be sure to edit the above.

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