Question

1. You have 15 apples and 25 oranges. Write the ratio

for the number of apples to oranges.
2. Solve the proportion:
X 10
9
12
=
3. The scale factor for the blueprints for a room is 1 in.
to 12 ft. . If the back wall of the room has the dimension
of 8 in. on the blueprints, how long is the actual length
back wall?

Answer 1

1. 3/5
2. x = 7.5
3. 96 ft

Explanation:

You want the solutions to various problems involving ratios, proportions, and scale factors.

1. Ratio

The ratio of 15 apples ot 25 oranges can be written several ways, with and without units:

15 apples to 25 oranges, or 15 to 25.

Reduced to 3 apples to 25 oranges, or 3 to 5

15 apples : 25 oranges, or 15 : 25

Reduced to 3 apples : 5 oranges, or 3 : 5

15 apples / 25 oranges, or 15/25

Reduced to 3 apples / (5 oranges), or 3/5

2. Proportion

You can solve the proportion ...

x/9 = 10/12

by multiplying both sides by 9:

x = 9·10/12 = 90/12

x = 15/2 = 7.5

3. Scale factor

If each inch represents 12 ft, then 8 inches represents 8·12 ft = 96 ft.

The actual length of the back wall is 96 feet.

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