A pilot flew a jet from City A to City B, a distance of 1900 mi. On the return trip, the average speed was 20% faster than the outbound speed. The round-trip took 7 h 20 min.

Question

What was the speed from City A to City B?

Answer 1

7 hours and 20 min = 7 and 1/3 hours = 22/3 hours

1900 = R * (22/3- t) = (22/3)R - Rt

1900 = (1.2R) * t = 1.2Rt

The second equation says 1900/1/2 = Rt

1583.3 = Rt

Substitutes this into the first equation:

1900 = (22/3)R - 1583.3

Then R = (1900 + 1583.3)*3/22 = 475

1900 = 475 * (22/3- t)

4 = 22/3 - t

4 + t = 22/3

t = 22/3 - 4 = 22/3 - 12/3 = 10/3

From A to B: 475 mph for 4 hours

From B to A: 570 mph for 10/3 hours

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