A subway train makes six stops of equal length during its 21 km run. The train is actually moving for 20 min of the trip. At most how long can the train remain at each station if the average speed for the trip, including stops, is to be at least 36 km/h?
2007-09-03 19:18:50 · 2 answers · asked by j;lkj;lkj;lkj;lkj 2 in Science & Mathematics ➔ Mathematics
Average time taken for 21km at 36km/h= 21/36 h =7/12 h =0.5833h = 35 min
total time at stops=35 - 20 = 15 min
time at each stop = 15/6= 2.5 min
2007-09-03 20:06:32 · answer #1 · answered by m.m 2 · 0⤊ 0⤋
If you divide 21 km by 36 kmph, you get about 7/12th of an hour or 35 minutes. That means that the train can stop for a total of 15 minutes. Now there is a slight question of what constitutes a stop, which is related to the route. If we assume the route is circular, so it has the same starting point as an exiting point, the train can remain at each station (including the start/end) for 2-1/2 minutes.
2007-09-04 02:32:07 · answer #2 · answered by cattbarf 7 · 0⤊ 0⤋