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For the first 5 hours of a trip, a plane averaged 120 kilometers per h
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19 Feb 2015, 08:52
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Re: For the first 5 hours of a trip, a plane averaged 120 kilometers per h
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19 Feb 2015, 11:07
Average speed= \(\frac{TotalDistance}{TotalTime}\)
let the remaining time be x
total distance= 5*120+ x*180 total time= 5+x so we have \(170=\frac{5*120+ x*180}{5+x}\) solving for x ,we get x = 25 total time 30 hours >>D



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For the first 5 hours of a trip, a plane averaged 120 kilometers per h
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20 Feb 2015, 00:23
Answer = D. 30 Let the distance covered The speed of 180 = x Total time required \(= \frac{600}{120} + \frac{x}{180} = \frac{600+x}{170}\) x = 18*50*5 Total time required =\(5 + \frac{18*50*5}{180}= 5 + 25 = 30\)
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For the first 5 hours of a trip, a plane averaged 120 kilometers per h
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22 Feb 2015, 11:44



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Re: For the first 5 hours of a trip, a plane averaged 120 kilometers per h
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23 Feb 2015, 04:00
we could solve it using the alligations or mixtures formula too because all the 3 avgs. namely A1 =120 , A2 = 180 and Aw = 170 are given. also n1 is given, n2 is reqd. we know that (A2Aw)/(A1Aw) = n1/n2..pluggin the values yield 1/5 =5/n2 or n2 =25 . total time 5 + 25 =30 hrs.



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For the first 5 hours of a trip, a plane averaged 120 kilometers per h
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01 Mar 2015, 22:57
Bunuel wrote: For the first 5 hours of a trip, a plane averaged 120 kilometers per hour. For the remainder of the trip, the plane traveled an average speed of 180 kilometers per hour. If the average speed for the entire trip was 170 kilometers per hour, how many hours long was the entire trip?
A. 15 B. 20 C. 25 D. 30 E. 35
Kudos for a correct solution. we can treat this question as a set theory question with mean of 170 . we know that first 5 elements are 120, 120,120, 120,120 , they all lag by 50 to meet the average of 170 , in sum lag by 250 . how many 180 should be put in order to fill this gap of 250 , if by adding one 180 we get 10 points (as the avg is 170) ? we need to add 25 180s . hence 25 hrs plane has to be driven at 180kmph so total time will be 25+5=30 thanks Lucky Consider +1 Kudos if you like this post.



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Re: For the first 5 hours of a trip, a plane averaged 120 kilometers per h
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11 Jan 2017, 03:23
Tug of War Method Let H hrs @ 170
[170120] x 5 = [180170] x H =>50x5 = 10xH =>H = 25
So Total 25+5=30. Ans D



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For the first 5 hours of a trip, a plane averaged 120 kilometers per h
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21 Apr 2018, 06:59
Bunuel VeritasPrepKarishma chetan2u niks18any alternate way to solve using thisblog?
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Re: For the first 5 hours of a trip, a plane averaged 120 kilometers per h
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21 Apr 2018, 18:12
adkikani wrote: Hi adkikaniCan you explain what is your exact query here? If you are confused with the use of too many formulas, then you can always solve these type of questions using the simple concept of average speed. Average Speed = Total Distance / Total Time & Speed = Distance / Time For e.g let's take the 3rd question from the blog. There are three parts to the journey and we are given speed and distance of each part. So find out the time taken to travel each part  30 miles @ 30 miles/hr, So time taken = 30/30=1 hr 30 miles @ 60 miles/hr, So time taken = 30/60=1/2 hr 30 miles 90 miles/hr, So time taken = 30/90=1/3 hr Total distance traveled = 30+30+30=90 miles Total Time taken = 1+1/2+1/3=11/6 hrs Hence Average Speed = 90/(11/6)=90*6/11=540/11



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Re: For the first 5 hours of a trip, a plane averaged 120 kilometers per h
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21 Apr 2018, 20:36
adkikani wrote: one just need to apply average speed formula Av speed=Total distance/total time Let total time be t So eqn would be 170=(120*5 + 180*(t5)) /t Calculate t and add 5 u Will find answer Posted from my mobile device
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Re: For the first 5 hours of a trip, a plane averaged 120 kilometers per h
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21 Apr 2018, 22:05
niks18The OE for this is as posted by push12345 but I wanted to reduce calculation mistakes in solving linear equation, if possible by an alternate solution.
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Re: For the first 5 hours of a trip, a plane averaged 120 kilometers per h
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21 Apr 2018, 22:41
adkikani wrote: niks18The OE for this is as posted by push12345 but I wanted to reduce calculation mistakes in solving linear equation, if possible by an alternate solution. Hi adkikaniOk I got your concern now. Refer to the blog whose link you had posted in your earlier post. In the blog you have below mentioned formula  t1/t2 = (A2 – Aavg)/(Aavg – A1), now use it to calculate the missing value t2 5/t2=(180170)/(170120) =>t2=25 Hence total time taken = t1+t2=5+25=30 Hope this helps



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Re: For the first 5 hours of a trip, a plane averaged 120 kilometers per h
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23 Apr 2018, 04:15
Hi, similar to the solution posted by niks18, but in diagrammatic form. This can also be solved using Mixture and Alligation method. Attachment:
Distance.png [ 3.79 KiB  Viewed 1505 times ]
T1:T2 = 10:50 = 1:5, Since T1 = 5 hrs => T2 = 5*5 = 25 hrs. Total time = T1 + T2 = 5 + 25 = 30 hrs. Thanks.



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Re: For the first 5 hours of a trip, a plane averaged 120 kilometers per h
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23 Apr 2018, 04:38
in first five hours plane covers 120*5 = 600kms let say plane covered rest of the journey in t hours so total distance covered in (5+t) hours = 600 + 180*t
Now average speed = total distance travel / total time taken
=> 170 = (600+180*t)/(5+t) ==>850 +170t = 600 + 180*t =>250 = 10t therefore, plane averaged 180 for the 25 hours
so total time taken = 5 + 25 = 30hours




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