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How can I use the area to find the cost?
Goal:
Goal:
Think About It!
Goal: Calculate the cost of something by finding the area.
A hot air balloon. The hot air balloon is 10 feet high and 1 section of the balloon is 4 feet wide.
Recall that area the number of unit squares needed to cover a flat surface. It is the entire amount of space inside a space or figure, like the size of the panel on the hot-air balloon.
Area is always given in square units. Click the words below to see how unit squares and area are related.
Unit Square
A unit square is a unit, or tile, in the shape of a
square that has the same length and width. A unit
square is written as in\({^2}\),
cm\({^2}\),
mm\({^2}\),
km\({^2}\) or
sq. units.
A grid, row 1 : Numbers 1 , 2, 3 row 2 : Numbers 4 , 5, 6 row 3 : Numbers 7 , 8 , 9 The area equals 9 square units. 1 unit by 1 unit equals a square unit.
Area
Area is the number of squares needed to cover a flat surface.
A grid, row 1 : Numbers 1 , 2, 3 row 2 : Numbers 4 , 5, 6 row 3 : Numbers 7 , 8 , 9 The area equals 9 square units.
As Madelyn and her family prepare for the festival, they need to calculate the cost to repair their balloon. The fabric comes in rectangular sheets that are sewn together to fix the balloon.
Click on the steps below to see how to calculate the cost of each panel for the hot-air balloon.
When you want to find the area of a rectangle, you multiply the number of square units in the length by the number of square units in the width. The length is how long the shape is. The width is how wide the shape is.
In other words, area = length \({\times}\) width, or area = \({l \times w}\) .
A hot air balloon. The hot air balloon is 10 feet high and 1 section of the balloon is 4 feet wide.
Area \({=}\) 10 feet \({\times}\) 4 feet \({=}\) 40 square feet or 40ft\({^2}\)
When you want to find the cost of something, it is important to look at the unit cost, or the cost of the item per square unit. Madelyn can purchase the necessary fabric for $5 per square foot. This means that every 1 square foot of fabric will cost $5.
1 unit by 1 unit \({=}\) 1 square unit. \({\times}\) cost per square unit \({=}\) Total cost of area.
The cost is $5 per ft\({^2}\). The total area is 40 ft\({^2}\). We can multiply to find the cost of one panel of fabric. 40 is a multiple of 10, so we can multiply \({4 \times 5}\) to get 20 and then add the zero from the 40. 40 ft\({^2}\) \({\times}\) $5 per ft\({^2}\) = $200. It is important to use units!
A hot air balloon.
Use what you know! If the cost per panel is $200 and there are 3 panels to be repaired, then the total cost of the balloon repair is $600! Multiply \({$200 \times 3 = 2 \times 3 = 6}\) and then add the two zeros at the end of 200. \({$200 \times 3 = $600}\).
Let's see if we can help Madelyn calculate the cost using other types of fabric.