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

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Bunuel
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A certain pilot flew 400 miles to City K at an average speed of 350 [#permalink] New post   01 Jul 2017, 00:40
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68% (02:26) correct 32% (02:31) wrong based on 197 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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B
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Luckisnoexcuse
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Re: A certain pilot flew 400 miles to City K at an average speed of 350 [#permalink] New post   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] New post   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] New post   31 Oct 2018, 10:49
average speed=2S1*S2/S1+S2
=2*350*250/350+250
=291.6 ANS
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Re: A certain pilot flew 400 miles to City K at an average speed of 350 [#permalink] New post   22 Aug 2020, 22:07
don't we have to consider the affect of "wind"?
I thought the time, with the wind, would be shorter than without wind(400/350).
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Re: A certain pilot flew 400 miles to City K at an average speed of 350 [#permalink] New post   22 Aug 2020, 23:52
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Distance is same , hence Average speed = \(\frac{2 * a * b }{ a + b}\)

=> \(\frac{2 * 250 * 350 }{ 250 + 350}\)

=> \(\frac{2 * 250 * 350 }{ 600 }\)

=> 291.66

Answer B
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Re: A certain pilot flew 400 miles to City K at an average speed of 350 [#permalink] New post   17 Apr 2022, 14:22
ashudhall wrote:
total time taken=400/350+400/250=96/35
total distance traveled = 400+400=800
average speed=800*35/96=291.66
hence B


Hi ashudhall, thanks for explanation. Not sure why 96/35 is being flipped into 35/96 in speed calculation? Thanks
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Re: A certain pilot flew 400 miles to City K at an average speed of 350 [#permalink]
17 Apr 2022, 14:22
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