Weighted Mean Problems Exercise Question #3

GRE Quant Problem Solving
1

Hi there,

I was curious why the calculation in the weighted mean solution is in minutes, instead of converted to hours. The solution is also left as is, not converted from km/min to km/h as the question asks. Appreciate any insight as to why this is correct. I calculated the 120 kmh and 80 kmh speeds correctly by substituting hour measurements instead of minutes into the d=st formula. But then for the weighted mean it uses the kmh speed multiplied by the minutes (not hours)?

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Thanks

2

What do you think the unit for the numerator is?

3

The numerator in the solutions looks to be Speed in kmh X Time in minutes - and the denominator is Time in minutes - I’m just not understanding why that yields a correct answer as I’ve been tripped up by not doing unit conversion in past questions, and this time when I did it got the wrong answer.

4

Are you proposing that it should be this instead \frac{120 \cdot \frac 13 + 0 \cdot \frac 16 + 80 \cdot \frac 14}{\frac 34}?