how long will it take to travel 21 miles at 40mph?

21 / 40 = .525 hours or 31.5 minutes

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40 / 60 = .667 miles per minute

21 / .667 = 31.5

At 40 mph you are going 40 miles per 60 minutes. Which if you condense is 40/60 = 2 miles each 3 minutes. You go 1 mile each 1 1/2 minutes. 21 times 1 1/2 is 31 1/2.

So you would take 31 min and 30 seconds.

21 Mile Drive

Mathematically speaking it would be a little more then a half hour. Considering MPH stands for “miles per hour” so if you are going 40mph it should take you an hour to go 40 miles. So 21miles is a little more then a half of that, so it should take a little more then a half an hour.

40 miles take 1 hour

1 mile takes 1/40 hour

21 miles take 21/40 = .525 hour = 31 minutes and 30 seconds

29 minutes 4 seconds

29 1/2 Minutes with no traffic and mild downhill speedups.

32 1/2 with MINIMAL traffic, some speedups, some stops.

38 Minutes, with MEDIUM traffic, slowdowns, stops, etc

45 Minutes with a heavy traffic jam, multiple stops. red lights.

4 hours if you gotta have hot sex with your girlfriend at a park or something...

(31.5 yes is the exact time mathmatically)

about 30 minutes,

just do the math

A bit.