Driving

Algebra Level pending

You are driving on a back road you are going twenty miles per hour and there is a stop light every other mile. Assuming each stop light is red (You should know the feeling if you are older than 16), each stop light takes 2 minutes to go from red to green. How far will you be in eighty minutes?

About 22 13.3 About 15.5 19 20 About 13.3 15.5 22

Joseph Devall by Joseph Devall , 17, USA

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2 solutions

Saya Suka
Mar 27, 2021

distance
= 80 * 2 / (3 + 3 + 2)
= 80 × 2 / 8
= 20 miles

80 minutes total time, divided by how long it takes to move from one stop light to the next (equals 3 gas-stepping minutes + 3 brake-stepping minutes + 2 greenlight-waiting minutes = 8 accumulated minutes per drive cycle) to get the number of repeating cycles and multiply it back to the distance per cycle (stop lights at every other miles).

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Twenty mph = 20 in 60.
Equivalent to 2 miles in 6 moving minutes.
Plus 0 miles moved in 2 pausing minutes for a cycle of 2+0 miles distance covered within 6+2 minutes.

Saya Suka - 2 months, 2 weeks ago
Joseph Devall
Jan 11, 2017

Find out how fast you are going per second and you find that you are going 1 3 \frac{1}{3} of a mile then you multiply that by how long of time you have (40 minutes)

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You are given 80 minutes to move, and you said after 40 minutes of pure moving, you'd reach 13.33 right, but by that distance, there would only be 6 red lights, a total of 12 minutes waiting / stopping. What about the extra 28 minutes?

Saya Suka - 4 years, 5 months ago

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