Charlie takes 2.5 hours to fly from Los Angeles to Mexico City, a dist

Hi All,

We're told that Charlie takes 2.5 hours to fly from Los Angeles to Mexico City, which is a total distance of 1200 miles. We're asked for the average speed of his plane in miles per hour. This is a straight-forward 'Average Speed' question, so we can just plug in the numbers at get the answer. There is a minor math move that you can make to save you some effort though...

Total Distance = (Av. Sp.)(Total Time)
1200 = (Av.Sp.)(2.5 hours)
1200/2.5 = Av.Sp.

At this point, instead of dividing 1200 by 2.5, you might find it useful to multiply both the numerator and denominator by 2 (to get rid of the decimal point):
2400/5 = Av.Sp.
480 = Av.Sp.

Final Answer:

GMAT assassins aren't born, they're made,
Rich