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# If John traveled a trip at a constant rate 20 miles per hour for 30 mi

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If John traveled a trip at a constant rate 20 miles per hour for 30 mi  [#permalink]

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Updated on: 01 Oct 2016, 05:31
00:00

Difficulty:

5% (low)

Question Stats:

87% (01:36) correct 13% (02:12) wrong based on 122 sessions

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If John traveled a trip at a constant rate 20 miles per hour for 30 minutes and at a constant rate 30 miles per hour for the remaining 20 minutes, what is the his average speed, in miles per hour?

A. 20
B. 24
C. 30
D. 32
E. 36

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Originally posted by MathRevolution on 01 Oct 2016, 01:58.
Last edited by abhimahna on 01 Oct 2016, 05:31, edited 1 time in total.
Edited the question.
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Re: If John traveled a trip at a constant rate 20 miles per hour for 30 mi  [#permalink]

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01 Oct 2016, 02:54
MathRevolution wrote:
If John traveled a trip at a constant rate 20 miles per hour for 30 minutes and at a constant rate 30 miles per hour for the remaining 20 minutes, what is the his average speed, in miles per hour?
A. 20miles B. 24miles C. 30miles D. 32miles E. 36miles

This is NOT a mixture question. It's distance/rate question. Edited.
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Re: If John traveled a trip at a constant rate 20 miles per hour for 30 mi  [#permalink]

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01 Oct 2016, 05:30
MathRevolution wrote:
If John traveled a trip at a constant rate 20 miles per hour for 30 minutes and at a constant rate 30 miles per hour for the remaining 20 minutes, what is the his average speed, in miles per hour?
A. 20miles B. 24miles C. 30miles D. 32miles E. 36miles

Distance = Speed * time

D1 = 20 * 1/2 = 10 Miles.

D2 = 30 * 1/3 = 10 Miles.

Avg Speed = Total Distance/ Total Time = 20/(1/3 + 1/2 ) = 24 miles per hour.

Also, Options should not have miles in it. We are calculating speed and not distance, The units of speed are already mentioned in the question stem.
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Re: If John traveled a trip at a constant rate 20 miles per hour for 30 mi  [#permalink]

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03 Oct 2016, 00:59
==> Average speed=the sum of distances/the sum of hours taken
John travelled 10 miles because he travelled at 20 mph for 30 minutes, and also travelled another 10 miles since he travelled at 30mph for 20 minutes. This leads to
Average Speed = (10miles+10miles)/(30min.+20min.)=24miles/1hour

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Re: If John traveled a trip at a constant rate 20 miles per hour for 30 mi  [#permalink]

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03 Feb 2018, 07:27
abhimahna wrote:
MathRevolution wrote:
If John traveled a trip at a constant rate 20 miles per hour for 30 minutes and at a constant rate 30 miles per hour for the remaining 20 minutes, what is the his average speed, in miles per hour?
A. 20miles B. 24miles C. 30miles D. 32miles E. 36miles

Distance = Speed * time

D1 = 20 * 1/2 = 10 Miles.

D2 = 30 * 1/3 = 10 Miles.

Avg Speed = Total Distance/ Total Time = 20/(1/3 + 1/2 ) = 24 miles per hour.

Also, Options should not have miles in it. We are calculating speed and not distance, The units of speed are already mentioned in the question stem.

Hi abhimahna

hope you are having fantastic weekend i switched to rate/distance problems, can you explain how you got Time 1 and Time 2 ? please

thanks!
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Re: If John traveled a trip at a constant rate 20 miles per hour for 30 mi  [#permalink]

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03 Feb 2018, 09:19
1
dave13 wrote:
Hi abhimahna

hope you are having fantastic weekend i switched to rate/distance problems, can you explain how you got Time 1 and Time 2 ? please

thanks!

Hey dave13 ,

Thanks for tagging.

We are given time in Minutes while speed in miles/hour. So, we should convert the given times in hour.

We are given 30 minutes for T1, meaning 1/2 hour.

Similarly, 20 minutes for T2, meaning 1/3 hour.

Does that make sense?
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Re: If John traveled a trip at a constant rate 20 miles per hour for 30 mi   [#permalink] 03 Feb 2018, 09:19
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