Question

Please help I have spent hours trying to do...

Answer 1

1. 914.4 mm
2. 0.0479594 km

Explanation:

For units conversion, use a conversion factor ratio with the units you do want in the numerator and the units you don't want in the denominator. The numbers in the numerator and denominator give the ratio a value of 1: the numerator is equal to the denominator--just in different units.

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1. For feet to mm, you need a couple of additional conversion factors besides the ones shown:

1 foot = 12 in

1 cm = 10 mm

So, the conversion is ...

`(3\text{ ft})*\frac{12\text{ in}}{1\text{ ft}}*\frac{2.54\text{ cm}}{1\text{ in}}*\frac{10\text{ mm}}{1\text{ cm}}=3*12*2.54*10\text{ mm}\\\\=\boxed{914.4\text{ mm}}`

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2. The additional factor you need for this problem is ...

1 mile = 5280 feet

So, the conversion is ...

`(157\text{ ft})*\frac{1\text{ mi}}{5280\text{ ft}}*\frac{1\text{ km}}{0.62\text{ mi}}=(157)/(5280*0.62)\text{ km}\\\\\approx\boxed{0.0479594\text{ km}}`

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Additional comment

You can use Google to do units conversion by typing "3 feet to mm" or "157 feet to km". However, the conversion factor for the latter will be more exact than the one given in this problem. Hence the Google answer to the second question will not be applicable here.