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A certain pilot flew 400 miles to City K at an average speed of 350

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Joined: 02 Sep 2009
Posts: 58381
A certain pilot flew 400 miles to City K at an average speed of 350  [#permalink]

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01 Jul 2017, 00:40
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Difficulty:

65% (hard)

Question Stats:

66% (02:24) correct 34% (02:39) wrong based on 107 sessions

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A certain pilot flew 400 miles to City K at an average speed of 350 miles per hour with the wind and made the trip back at an average speed of 250 miles per hour against the wind. Which of the following is closest to the pilot’s average speed, in miles per hour, for the round-trip?

(A) 280
(B) 290
(C) 300
(D) 310
(E) 320

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Re: A certain pilot flew 400 miles to City K at an average speed of 350  [#permalink]

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01 Jul 2017, 00:59
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Bunuel wrote:
A certain pilot flew 400 miles to City K at an average speed of 350 miles per hour with the wind and made the trip back at an average speed of 250 miles per hour against the wind. Which of the following is closest to the pilot’s average speed, in miles per hour, for the round-trip?

(A) 280
(B) 290
(C) 300
(D) 310
(E) 320

Distance traveled = 800

T = (400/350) + (400/250) = (8/7) + (8/5) = 96/35 Hrs

Speed = (800/96)*35 = 3500/12 = ~291

Hence B
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Re: A certain pilot flew 400 miles to City K at an average speed of 350  [#permalink]

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01 Jul 2017, 02:31
total time taken=400/350+400/250=96/35
total distance traveled = 400+400=800
average speed=800*35/96=291.66
hence B
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Re: A certain pilot flew 400 miles to City K at an average speed of 350  [#permalink]

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31 Oct 2018, 10:49
average speed=2S1*S2/S1+S2
=2*350*250/350+250
=291.6 ANS
Re: A certain pilot flew 400 miles to City K at an average speed of 350   [#permalink] 31 Oct 2018, 10:49
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