First, we need to convert the scale from centimeters to feet. Since 1 cm represents 10 ft, we can write:
1 cm/10 ft
To find how far apart the actual trees should be planted (in feet), we need to multiply the distance in the diagram (in centimeters) by the scale factor (in feet per centimeter). We can set up a proportion:
5 cm * (1 cm/10 ft) = x ft * (1 cm/9 cm)
Simplifying the units:
5/10 ft = x/9 cm
Cross-multiplying:
5 * 9 = 10 * x
x = 4.5 ft
Therefore, the actual trees should be planted 4.5 feet apart.