The proportion 15/x = 1/12 or 1/12 = 15/x is used to determine the height of the building option fourth is correct.
Fraction number consists of two parts, one is the top of the fraction number which is called the numerator and the second is the bottom of the fraction number which is called the denominator.
We have:
An apartment building has 15 floors. Each floor is about 12 feet high.
Let's suppose the height of the building is x feet
1 floor = 12 feet
15 floors = x feet
x/15 = 12/1
or
15/x = 1/12
Thus, the proportion 15/x = 1/12 is used to determine the height of the building option fourth is correct.
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