Question

If a student can run the mile in 8 minutes, how many miles can they run in an hour?

Answer 1

The answer is: " 7
`(1)/(2)`
`(mi )/(hr)` " ;

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or, write as: " 7. 5
`(mi)/(hr)` " .

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Step-by-step explanation:

To solve:

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Using a technique called "dimensional analysis" :

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`(1 mi)/(8 min)` *
`(60 min)/(1 hr)` ;

=
`((1 * 60))/((8 * 1 ))`
`(mi)/(hr)`

=
`(60)/(8)`
`(mi)/(hr)` ;

=
`((60/4))/((8/4))`
`(mi)/(hr)` ;

=
`(15)/(2)`
`(mi)/(hr)` ;

= { 15 ÷ 2 }
`(mi)/(hr)`

= " 7
`(1)/(2)`
`(mi )/(hr)` " .

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or, write as: " 7. 5
`(mi)/(hr)` " .

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