Problem Solving

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: D

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

BTGmoderatorLU wrote:Source: Magoosh

Charlie takes 2.5 hours to fly from Los Angeles to Mexico City, a distance of 1200 miles. What is the average speed of his plane in miles per hour?

A. 200 mph
B. 240 mph
C. 410 mph
D. 480 mph
E. 533 mph

The OA is D

Average speed = (total distance traveled)/(total travel time)

So, Average speed = 1200/2.5 = 2400/5 = 4800/10 = 480 mph

Answer: D

Cheers,
Brent

BTGmoderatorLU wrote:Source: Magoosh

Charlie takes 2.5 hours to fly from Los Angeles to Mexico City, a distance of 1200 miles. What is the average speed of his plane in miles per hour?

A. 200 mph
B. 240 mph
C. 410 mph
D. 480 mph
E. 533 mph

We can use the formula:

average = (total distance)/(total time)

average = 1200/2.5 = 480 mph

Answer: D