M14-06

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Bunuel

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Re M14-06 [#permalink]

16 Sep 2014, 00:51

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Official Solution:

If an athlete ran the first half of a 200-meter race in 10 seconds and the second half in 12 seconds, by how much was his average speed over the first half larger than that over the second?

A. 2.0 km/h
B. 3.0 km/h
C. 3.6 km/h
D. 6.0 km/h
E. 7.2 km/h

The runner's average speed over the first 100 meters was 10 m/s or $3600*\frac{10}{1000} = 36$ km/h. The runner's average speed over the second 100 meters was $\frac{100}{12}$ m/s or $3600*\frac{100}{12*1000} = 30$ km/h. The difference is 6 km/h.

Answer: D
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Mermaidk

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Re: M14-06 [#permalink]

08 Dec 2016, 08:47

Kudos

I don't like how you don't post the conversion formulas. On the test the formulas are provided thus your questions without them are unrealistic and unnecessarily difficult.

Bunuel

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Re: M14-06 [#permalink]

08 Dec 2016, 13:48

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Mermaidk wrote:

I don't like how you don't post the conversion formulas. On the test the formulas are provided thus your questions without them are unrealistic and unnecessarily difficult.

This type of questions are called conversion problems and they never provide with any formula.

Check other Conversion problems to practice from our Special Questions Directory.
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Voksu

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Re: M14-06 [#permalink]

09 Oct 2017, 19:15

Could you please explain this part 3600∗[10][/1000]=36 kmh

chetan2u

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Re: M14-06 [#permalink]

09 Oct 2017, 19:45

Kudos

Expert Reply

Voksu wrote:

Could you please explain this part 3600∗[10][/1000]=36 kmh

Hi...
You have to convert m into km and sec into h...
So 10m/s
1m= 1/1000 km ..... 10m=10/1000
1hour=60minutes..
And 1minute=60sec, so 1h =60*60 sec=3600sec
Therefore 1sec=1/3600 h...
Substitute in 10m/s....
(10/1000)/(1/3600)=3600*10/1000 kmph..
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Amit700

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Re: M14-06 [#permalink]

14 Oct 2019, 11:25

It should be Kmph in the answer choice, right?

Bunuel

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Re: M14-06 [#permalink]

14 Oct 2019, 20:56

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Amit700 wrote:

It should be Kmph in the answer choice, right?

Yes. Kilometre per hour, kmph or km/h.
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Re M14-06 [#permalink]

11 Jun 2020, 05:17

Kudos

I think this is a high-quality question and I agree with explanation.

AnirudhaS

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Re: M14-06 [#permalink]

25 Apr 2021, 10:37

Am I the only one who did not assume that the first half was equal to the second?
I went with d meters = first half, hence second half was (100-d) metres

ib1703

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Re: M14-06 [#permalink]

15 Aug 2021, 09:03

Somehow it was difficult to understand.

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Re: If an athelete ran the first half of a 200 meter race in 10 [#permalink]

12 Dec 2021, 11:08

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