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**Answer:**

(b) 1 foot = 3/8 inch

**Step-by-step explanation:**

The given ratio is ...

actual : scale = 4" : 1/8"

You know that 1 foot = 12 in = 3×4 in, so you can multiply the above ratio by 3 to see what it is for 1 foot.

actual : scale = 3×4" : 3×1/8"

= 12" : 3/8"

= **1 foot : 3/8 in**

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<em>Alternate approach</em>

Essentially, we're saying that the ratios between actual measures and those on a scaled drawing or model form a proportion.

scale / actual = (1/8")/(4 in) = ??/(12 in)

Multiplying by 12 in, we get ...

?? = (12 in)(1/8")/(4 in) = 3×1/8"

** ?? = 3/8"**

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<em>More detail</em>

Notice that this only works when the units in the ratio (12 in)/(4 in) cancel to give a pure number 12/4 = 3.

If we had put 1 foot in the proportion, then we would end up with ?? being expressed in feet, not inches:

(1/8")/(4") = ??/(1 ft)

?? = (1 ft)(1/8")/(4") = (1 ft)(1/32) = 1/32 ft

Then, to find the answer to the question, we would have to find out how many inches is 1/32 ft.

1/32 ft = (1/32)(12 in) = 12/32 in = 3/8 in

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<em>End comment</em>

For best results, the units in corresponding parts of a proportion should be the same.