Re: Half an hour after car A started traveling from Newtown to
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29 Oct 2017, 01:56
Let's see which information we have. Car A has traveled 45 minutes at a speed 8m/h greater than car B speed (x). Car B traveled 15 minutes at speed x m/h.
Since they meet along a road 62 km long, it must be that the distance the two cars traveled sum to 62. Thus, we can proceed by plugging-in the choices we have and check if they do the job. Let's start from the middle one, C = 10 m.
If car B would have traveled 10 m, its speed would have been 10/(1/4) = 40 m/h (15 minutes is 1/4 of hour). Thus, car A speed would have been 48 m/h and it would have been traveled for 48*(3/4) = 24 m. Then, 10m+24m = 34m < 62 m. Thus, choice C is not our answers. We have to look for something higher.
If we proceed with this same kind of check we get that if car B traveled for 14m, then its speed is 14/(1/4) = 56 m/h so that car B speed is 64 m/h and it traveled for 48m, which summed to 14 gives us 62, the length of the road.
Answer A