Problema Solution
The subway train offers access to all twelve intersections downtown. If every intersection is .75 miles apart and the train travels at 20 mph and spends 45 seconds at every stop to unload and onboard new customers, how long will it take to get from the first intersection to the last intersection?
Answer provided by our tutors
The total distance between the first and the last intersection is:
(12 - 1)*0.75 = 11*0.75 = 8.25 mi
The time the train needs to travel 8.25 mi without stopping is:
8.25/20 = 0.4125 hr = 24 min 45 sec
We will assume the train onboards new customers at each stop, starting from the first stop.
Starting from the first till the twelfth stop there are 11 stops (not counting the last one since we need the time of the arriving at the last stop) by 45 second or total of 11*45 = 495 sec = 8 min 15 sec.
We add the two times:
24 min 45 sec + 8 min 15 sec = 33 min
It will take 33 minutes to get to the last intersection.