Problema Solution

A pilot is testing a new experimental craft. The cruising speed is classified information. In a test the jet traveled 4,000 miles. The pilot revealed that if he had increased his speed 200 mph, the total trip would have taken 1 hour less. Determine the cruising speed of the jet.

Answer provided by our tutors

let


d = 4,000 mi the distance traveled


v = the cruising speed of the jet, v>0


t = d/v the time of the trip (since speed = distance/time => time = distance/speed)


t = 4000/v


The pilot revealed that if he had increased his speed 200 mph, the total trip would have taken 1 hour less


the increased speed is: v + 200


the time of the trip: t - 1


t - 1 = d/(v + 200)


plug d = 4,000 and t = 4000/v into the last equation:


(4000/v) - 1 = 4000/(v + 200)


by solving we find


v = 800 mph


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the cruising speed of the jet is 800 mph.