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The Kiljaro Highway is marked with Milestones denoting the [#permalink]
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09 Jul 2013, 01:28
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75% (03:21) correct
25% (03:06) wrong based on 135 sessions
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The Kiljaro Highway is marked with Milestones denoting the distance to the town of Kiljaro. Tommy left kiljaro and drove the highway, passing the 10 km milestone at 8:30. Some time afterwards, Tommy got a phone call asking him to return home, and he made a Uturn at the 160 km milestone. At 09:A0 Tommy passed the milestone marking 70 km to Kiljaro. The variable A represents the tens digit of the minutes in 09:A0. Assuming Tommy maintained the same constant speed during the entire drive, how many kilometers did Tommy travel in one minute? A. 240/(30+10A) B. 240/(30+60A) C. 240/40A D. 220/(30+10A) E. 220/40A P.S: Bunuel/VeritasPrepKarishma can you please provide an explanation and how to approach this type of questions in least possible time? It took around 4 minutes to understand and solve!
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Re: The Kiljaro Highway is marked with Milestones denoting the [#permalink]
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09 Jul 2013, 01:45
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Total distance covered away from Kilijaro: 16010 = 150km Total distance covered till 9:A0 while returning to Kilijaro: 16070 = 90 Total distance covered between 8:30 and 9:A0: 150 + 90 = 240 Total time elapsed between 8:30 and 9:A0 = 30 (From 8:30 to 9:00) + 10*A = 30 + 10.A minutes Speed per minute = 240 / (30 + 10.A) Answer should be 'A'



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Re: The Kiljaro Highway is marked with Milestones denoting the [#permalink]
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31 Dec 2013, 13:58
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bagdbmba wrote: The Kiljaro Highway is marked with Milestones denoting the distance to the town of Kiljaro. Tommy left kiljaro and drove the highway, passing the 10 km milestone at 8:30. Some time afterwards, Tommy got a phone call asking him to return home, and he made a Uturn at the 160 km milestone. At 09:A0 Tommy passed the milestone marking 70 km to Kiljaro. The variable A represents the tens digit of the minutes in 09:A0. Assuming Tommy maintained the same constant speed during the entire drive, how many kilometers did Tommy travel in one minute?
A. 240/(30+10A) B. 240/(30+60A) C. 240/40A D. 220/(30+10A) E. 220/40A
P.S: Bunuel/VeritasPrepKarishma can you please provide an explanation and how to approach this type of questions in least possible time? It took around 4 minutes to understand and solve! So he travelled first 150 km from 10 to 160km Then he travelled 90 km more for a total of 240 km So average time in km per minute will be expressed as 240 / (30 + 10A) Allow me to explain. 30 minutes 'till 9am. And then 10A is cause the A is in the tens digit So A is the correct answer Hope it helps! Cheers! J



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Re: The Kiljaro Highway is marked with Milestones denoting the [#permalink]
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11 Jul 2013, 01:36



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Re: The Kiljaro Highway is marked with Milestones denoting the [#permalink]
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12 Jul 2013, 04:31
Consider 8:30 am to be starting point . Then there are two journeys.
1) From the 10km mark to 160 km: Let the time taken to travel this be x
\(Speed =\frac{150}{x}\)
2) From 160km to 70 km: This journey starts at time "x" till time "9:A0"
Thus the \(time taken = (time from 8:30 to 9:A0)  x\) = \((30 + 10A)  x\) \(Speed = \frac{(160  70)}{[ (30+10A) x ]} = \frac{90}{[ (30+10A) x ]}\)
But speed is uniform, so...
\(150/x = \frac{90}{[ (30+10A) x ]}\)
Solving this gives \(x = \frac{150(30 + 10A)}{240}\)
Distance travelled in a minute = \(Speed = \frac{150}{x} = \frac{240}{(30 + 10A)}\)



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Re: The Kiljaro Highway is marked with Milestones denoting the [#permalink]
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04 Aug 2013, 14:22
The Kiljaro Highway is marked with Milestones denoting the distance to the town of Kiljaro. Tommy left kiljaro and drove the highway, passing the 10 km milestone at 8:30. Some time afterwards, Tommy got a phone call asking him to return home, and he made a Uturn at the 160 km milestone. At 09:A0 Tommy passed the milestone marking 70 km to Kiljaro. The variable A represents the tens digit of the minutes in 09:A0. Assuming Tommy maintained the same constant speed during the entire drive, how many kilometers did Tommy travel in one minute?
From the 10km mark at 8:30 to the 160km milestone back to the 70km marker at 9:A0 Tommy traveled 240 km. That right there should help rule out D and E. We know Tommy traveled at least 30 minutes and A could represent 05 inclusive. Tommy's speed per minute is distance/time. We know he traveled 240 km and we know he traveled a minimum of 30 minutes. Therefore, Tommy's speed = 240/30+(10*A) where 10A represents the additional number of minutes (in 10 minute intervals) that Tommy covered.
Another way to do this is to find his average speed over the total possible number of minutes he drove (between 30 and 80 minutes) then see which answer choice matches up with the possible speeds he drove. This, however, is time consuming.
Also, to put things in perspective, Tommy's average speed was 288 km/hr or 180 miles/hour. Using the above method, I ruled out a few of his other possible speeds (540km/hour and 360 km/hour and 288 km/hour) because I figured them to be unrealistically fast. You can't count on the GMAT to employ realistic numbers, however.
ANSWER: A. 240/(30+10A)



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Re: The Kiljaro Highway is marked with Milestones denoting the [#permalink]
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17 Jan 2014, 19:26
Zuch wrote: Total distance covered away from Kilijaro: 16010 = 150km Total distance covered till 9:A0 while returning to Kilijaro: 16070 = 90 Total distance covered between 8:30 and 9:A0: 150 + 90 = 240 Total time elapsed between 8:30 and 9:A0 = 30 (From 8:30 to 9:00) + 10*A = 30 + 10.A minutes Speed per minute = 240 / (30 + 10.A) Answer should be 'A' Can't total distance calculated like this: 10+160+70? This equals 240 and the speed per minute would be 240/30+10A? Please explain if I am wrong.



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Re: The Kiljaro Highway is marked with Milestones denoting the [#permalink]
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23 Jan 2014, 00:06
Total distance traveled between 8:30 and 9:A0 is (16010)+(16070)=240.
Time between 8:30 and 9:A0 is (9:008:30)+(9:A09:00)=30+A*10
Total km traveled in one minute is total kilometers traveled divided by total minutes it took to travel that distance. 240/(30+10A)



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Re: The Kiljaro Highway is marked with Milestones denoting the [#permalink]
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27 Aug 2015, 01:23
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Re: The Kiljaro Highway is marked with Milestones denoting the [#permalink]
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27 Aug 2015, 03:23
IMO, the fastest way to solve this problem would just the logic: Here i think about it:
One minute distance = total distance/time in minutes
Total distance is =240km
time = 30 minutes (8:30 to 9)+<60 minutes ( i will not add time or distance starting 10 since the problem does not specify that, and whatever information is given is sufficient)
Now the next step is to look at the answer choices, and we can see A) Makes sense  denominator 30+10A with Max A <6 (as we have information for time below 10)
Hope this helps!



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Re: The Kiljaro Highway is marked with Milestones denoting the [#permalink]
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27 Aug 2015, 03:59
Hi,
Since we are dealing with the variables in the answer choices,the best possible method according to me would be "substitution". Substitute A with 3.meaning tommy would have travelled a distance of ((16010) + (16070)) in 60 minutes. 240 Kms in 60 minutes ==> 4km/hr.
Substitute A with 3 in the answer options. Option A
Cheers!!




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