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Bunuel
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Jack and Jill are marathon runners. Jack can finish a marathon (42 km) 08 Dec 2015, 03:12
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A
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Jack and Jill are marathon runners. Jack can finish a marathon (42 km) in 4.5 hours and Jill can run a marathon in 4.2 hours.What is the ratio of their average running speed? (Jack: Jill)

A. 14/15
B. 15/14
C. 4/5
D. 5/4
E. Cannot be determined
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A
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Jack and Jill are marathon runners. Jack can finish a marathon (42 km) Updated on: 08 Dec 2015, 05:07
Originally posted by CounterSniper on 08 Dec 2015, 03:28.
Last edited by CounterSniper on 08 Dec 2015, 05:07, edited 2 times in total.
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speed is inversely proportional to time
or
s1/s2=t2/t1
t1/t2=4.5/4.2=s2/s1
therefore.
Jack/jill=14/15
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Jack and Jill are marathon runners. Jack can finish a marathon (42 km) 08 Dec 2015, 04:24
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Average Speed of Jack =Distance/ Time
= 42 /(9/2) = 84/9

Average Speed of Jill = 42/(4.2) = 10

Ratio of Average speed of Jack to Jill = (84/9)/10 = 84/90 = 14/15

Answer A
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Jack and Jill are marathon runners. Jack can finish a marathon (42 km) 08 Dec 2015, 04:48
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jack speed =42/4.5

jill speed = 42/4.2

jack speed : jill speed 4.2 :4.5 =14/15
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Jack and Jill are marathon runners. Jack can finish a marathon (42 km) 09 Apr 2016, 14:26
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distance being the same for both the runners jack and jill. Ratio of speeds of jack to jill's speed will be inverse of ratio of time required by them to complete the marathon
(Jill's Time/Jack's Time) - 4.2/4.5 = 14/15
Correct answer - A
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Jack and Jill are marathon runners. Jack can finish a marathon (42 km) 24 Jun 2017, 08:14
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\(R= \frac{D}{T}\)
Rate of Jack = \(\frac{42}{4.5}\) and Rate of Jill = \(\frac{42}{4.2}\)

\(\frac{Jack}{Jill}=\frac{420}{45} * \frac{42}{420}\) = \(\frac{42}{45} = \frac{14}{15}\)

Answer is A
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Jack and Jill are marathon runners. Jack can finish a marathon (42 km) 04 Apr 2019, 18:51
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Bunuel
Jack and Jill are marathon runners. Jack can finish a marathon (42 km) in 4.5 hours and Jill can run a marathon in 4.2 hours.What is the ratio of their average running speed? (Jack: Jill)

A. 14/15
B. 15/14
C. 4/5
D. 5/4
E. Cannot be determined
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Jacks’ average speed is 42 km/4.5 hours, and Jill’s average speed is 42 km/4.2 hours. Thus, the ratio of their average speeds (Jack : Jill) is:

(42/4.5)/(42/4.2)

42/4.5 x 4.2/42

4.2/4.5

42/45

14/15

Answer: A
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Jack and Jill are marathon runners. Jack can finish a marathon (42 km) 18 Nov 2023, 05:44
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Hi everybody,


For some reason, I would tend to put the following 15/14 ratio and I would like to have your reasoning behind it.


Thank you for your help!
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