Christmas trees tend to be proportional in shape. You have a tree skirt that is circular and with diameter 3 feet, which you bought for a 7-foot tree. If you have a 5-foot tree this year, what size tree skirt will you need? (Round to the nearest size.)
A) a skirt whose diameter is 2.5 feet
B) a skirt whose diameter is 2 feet
C) a skirt whose diameter is 1.5 feet
D) a skirt whose diameter is 1 foot

Question

Quizplus · Accepted Answer

Since the trees are proportional, we can set up a proportion:

3 feet (diameter of skirt for 7-foot tree) is to 7 feet (height of tree) as x feet (diameter of skirt for 5-foot tree) is to 5 feet (height of tree).

This gives us the equation:

3/7 = x/5

Solving for x, we get:

x = (3/7) * 5

x = 2.143

Since we need to round to the nearest size, the closest diameter for the skirt is 2 feet (which is our option B).

Christmas Trees Tend to Be Proportional in Shape