Final answer:
To find how far apart Oakdale and Woodridge are on a map with a scale of 3 cm:18 km, a proportion is used. The calculation shows that the two locations are 9 cm apart on the map, corresponding to option (a).
Step-by-step explanation:
The student has asked how far apart Oakdale and Woodridge are on a map if the actual distance between them is 54 km and the map's scale is 3 cm:18 km. To find the distance on the map, we can set up a proportion. The scale means that for every 3 cm on the map, the actual distance represented is 18 km. We can set up the proportion as follows:
3 cm / 18 km = x cm / 54 km
To solve for x, we can cross-multiply:
(3 cm * 54 km) / 18 km = x cm
This simplifies to:
162 cm / 18 km = x cm
Which then simplifies to:
x = 9 cm
Therefore, on the map, Oakdale and Woodridge are 9 cm apart, which corresponds to option (a).