the solution seems to be simple. Just try to imagine what is happening You have a road with downhill and uphill. So if u travel 5 km uphill and then 5 km on plain and then 5 km on downhill then time taken by you will be equal to 15 km on the plain road(that is solely due avg of speed of downhill and uphill is = speed on plain road)
so the from A to B we reach 40 min earlier due to there more downhill road. while from A to B it is uphill. So let us take x km as the road distance which is not plain. t1 = time to travel x on downhill = x/72 t2 = time to travel x on uphill = x/56 but as given 40min = 2/3 hr = x/56 - x/72 so, x= 168. so it will take 3 hrs to climb while travelling from B to A and plain road distance = 5/3 * 64 = 106.67 km dist = 168 + 106.67 On Wed, Sep 15, 2010 at 8:21 AM, Terence <technic....@gmail.com> wrote: > > > You could also get a unique solution if the car has speed of 72 63 56 > > in downhill, plain and uphill respectively. > > I think the speed Vd, Vp, Vu was chosen so that 2Vp = Vd + Vu. > But for unique solution, it ought to be 2/Vp = 1/Vd + 1/Vu. > > Under this condition, we can get the unique S=x+y+z: > From > x/Vd + y/Vp + z/Vu = T1 > x/Vu + y/Vp + z/Vd = T2 > We get (1/Vu+1/Vd)(x+z)+2/Vp*y = T1+T2 > Apply 2/Vp = 1/Vd + 1/Vu, then 2/Vp(x+y+z)=T1+T2 > S=x+y+z = Vp(T1+T2)/2 > > > > On 2010-9-15 9:31, Gene wrote: > >> This isn't right. Dropping both y terms is the same as setting y to >> zero. The answer you get is correct, but there are many others as has >> been said. >> >> You could get a unique solution if the route were constrained to be >> monotonic (level and up or else level and down). >> >> On Sep 14, 4:28 pm, Minotauraus<anike...@gmail.com> wrote: >> >>> Actually the solution is unique. The middle part with the Ys is the >>> same and therefore can be omitted out. Now you are left with >>> 2 equations and 2 unknowns. >>> >>> I used time in minutes and I have x = 1.28, z = 0.30476 units (y can >>> be found out). >>> >>> I guess the trick was 1. to write the equations that Yan did >>> and 2. to recognize that the plain part is the same and hence can be >>> cancelled. >>> >>> On Sep 14, 3:31 am, Yan Wang<wangyanadam1...@gmail.com> wrote: >>> >>> >>> >>> actually, there are many solutions, just pick up one from them... >>>> On Tue, Sep 14, 2010 at 3:23 AM, Abhilasha jain >>>> <mail2abhila...@gmail.com> wrote: >>>> >>>>> how can u solve 3 variables using 2 equations? >>>>> On Tue, Sep 14, 2010 at 3:44 PM, Yan Wang<wangyanadam1...@gmail.com> >>>>> wrote: >>>>> >>>>>> x/72 + y/64 + z/56 = 4 >>>>>> & >>>>>> x/56 + y/64 + z/72 = 4+2/3 >>>>>> find a solution to this ... >>>>>> On Tue, Sep 14, 2010 at 2:31 AM, bittu<shashank7andr...@gmail.com> >>>>>> wrote: >>>>>> >>>>>>> Amazon Interview Question for Software Engineer / Developers >>>>>>> A car has speed of 72 64 56 in downhill, plain and uphill >>>>>>> respectively . A guy travels in the car from Pt. A to pt. B in 4 Hrs >>>>>>> and pt. B to pt. A in 4 Hrs and 40 min. what is the distance between >>>>>>> A >>>>>>> and B? >>>>>>> Regards >>>>>>> Shashank >>>>>>> -- >>>>>>> You received this message because you are subscribed to the Google >>>>>>> Groups "Algorithm Geeks" group. >>>>>>> To post to this group, send email to algoge...@googlegroups.com. >>>>>>> To unsubscribe from this group, send email to >>>>>>> algogeeks+unsubscr...@googlegroups.com<algogeeks%2bunsubscr...@googlegroups.com> >>>>>>> . >>>>>>> For more options, visit this group at >>>>>>> http://groups.google.com/group/algogeeks?hl=en. >>>>>>> >>>>>> -- >>>>>> You received this message because you are subscribed to the Google >>>>>> Groups >>>>>> "Algorithm Geeks" group. >>>>>> To post to this group, send email to algoge...@googlegroups.com. >>>>>> To unsubscribe from this group, send email to >>>>>> algogeeks+unsubscr...@googlegroups.com<algogeeks%2bunsubscr...@googlegroups.com> >>>>>> . >>>>>> For more options, visit this group at >>>>>> http://groups.google.com/group/algogeeks?hl=en. >>>>>> >>>>> -- >>>>> You received this message because you are subscribed to the Google >>>>> Groups >>>>> "Algorithm Geeks" group. >>>>> To post to this group, send email to algoge...@googlegroups.com. >>>>> To unsubscribe from this group, send email to >>>>> algogeeks+unsubscr...@googlegroups.com<algogeeks%2bunsubscr...@googlegroups.com> >>>>> . >>>>> For more options, visit this group at >>>>> http://groups.google.com/group/algogeeks?hl=en.- Hide quoted text - >>>>> >>>> - Show quoted text - >>> >> > -- > You received this message because you are subscribed to the Google Groups > "Algorithm Geeks" group. > To post to this group, send email to algoge...@googlegroups.com. > To unsubscribe from this group, send email to > algogeeks+unsubscr...@googlegroups.com<algogeeks%2bunsubscr...@googlegroups.com> > . > For more options, visit this group at > http://groups.google.com/group/algogeeks?hl=en. > > -- Regards, Rahul Patil -- You received this message because you are subscribed to the Google Groups "Algorithm Geeks" group. To post to this group, send email to algoge...@googlegroups.com. To unsubscribe from this group, send email to algogeeks+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/algogeeks?hl=en.
