Math CentralQuandaries & Queries


Question from Tamara, a student:
An object is traveling at a speed of 45 km/minute. How long will it take to make 50 miles?

We have two responses for you


You can do unit conversions using tables, a scientific calculator, or even Google: enter

[45 km/minute in miles per minute]

Once you have the answer in miles per minute, your problem is :

At (some number of) miles per minute how long does it take to make 50 miles?

You should should be able to solve directly, perhaps using a calculator. If you still find it tricky set up a parallel problem with very easy numbers of similar proportions (but don't use 1):

At 2 miles per minute how long does it take to make 6 miles?

Well, that was easy! Now, did you multiply or divide, and if you divided what did you divide? Now do the same with the real problem.

Good Hunting!


Hi Tamara.

Google keeps getting smarter.
Try typing 50 miles divided by 45 kilometers per minute into Google.


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