SOLUTION: Schools often have a section of street called a school zone located near their entrances. In a school zone, driving speeds are reduced at certain times of the day. If a school zone

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Question 551399: Schools often have a section of street called a school zone located near their entrances. In a school zone, driving speeds are reduced at certain times of the day. If a school zone is 0.3 miles long, how many minutes longer does it take to drive through it at 20 miles per hour that at 30 miles per hour?
Found 2 solutions by Earlsdon, Theo:
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
Starting with:
d+=+rt d = distance, r = rate/speed, and t = time of travel.
For this problem, we want to find the difference in the times when r = 20mph and r = 30mph over a distance of 0.3 miles.
At 30mph we have:
t%5B1%5D+=+0.3%2F30
t%5B1%5D+=0.01hours.
At 20mph we have:
t%5B2%5D+=+0.3%2F20
t%5B2%5D+=+0.015hours. Subtract t%5B2%5D-t%5B1%5D
0.015-0.01+=+0.005hours. Convert to seconds, multiply by 3600 seconds/hour.
0.005%283600%29+=+18seconds.
It takes 18 seconds longer at 20mph than it would at 30mph.

Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!
20 miles per hour times 5280 equals 105600 feet per hour divided by 60 equals 1760 feet per minute divided by 60 equals 29.3333333333 feet per second.
30 miles per hour times 5280 equals 158400 feet per hour divided by 60 equals 2640 feet per minute divided by 60 equals 44 feet per second.
.3 of a mile is equal to .3 * 5280 = 1584 feet.
at 20 miles per hour you are traveling 29.3333333333 feet per second.
divide 1584 feet by 29.3333333333 feet and you get 54 seconds.
at 30 miles per hour you are traveling 44 feet per second.
divide 1584 feet by 44 and you get 36 seconds.
it takes about 18 seconds more to go through the school zone at 20 miles per hour than it takes to go through the school zone at 30 miles per hour.