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It would take less than a half hour to travel 30 miles at 70 miles per hour.

Ways to figure out the driving time:

This problem is easily solved using ratios:

Traveling at 70 MPH = 70 miles / h = 70 miles / 60 minutes = 1.66667 miles / minute = 0.8571 minutes / mile.

Thus, at that rate, to travel 30 miles = 30 miles x 0.8571 minutes = 25.7143 minutes, or 25 minutes, 42.85 seconds.

Or, stated more simply, since 60MPH = 1 min/mile,

60MPH/70MPH=.8571 x 1 min/mile = .8571 min/mile x 30 miles; again = 25m:42.85s

I assume this is a serious question but you have the answer. It's basically using ratios or more formally, simple algebra, which I avoided for simplicity.

Most simply, starting with "60MPH = 1 mile/minute = 1 minute/mile" Any speed other than 60 MPH is a ratio of that.

You would use the exact same technique to measure your car's speedometer's accuracy by measuring the time between mile markers on a highway. Also, your odometer had better read 1.0 miles between markers as well.

Set your cruise control, or speed to exactly 60 on your speedometer (assuming that's a legal speed). Start timing from the time a mile marker passes your side mirror, until the next marker passes the same mirror. Any deviance from 60 seconds to your timing is the ratio your speedometer is off. So if it took 62 seconds between markers, 60/62=0.9677 x 60MPH = 58 MPH actual speed. etc. FYI, By law, automotive speedometers must read between exact, or a slightly HIGHER speed then actual to allow for a "safety factor". I believe it's only a few %, 5% at most.

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9y ago
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Q: How long would it take to travel 30 miles at 70 miles per hour?
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