Question

cindy is making a blanket for her grandchild. the trapezoid below represents a model of a shape used on the blanket.
trapezoid with top base 12 cm, bottom base 18 cm, height 9 cm, and scale 1 cm : 3 in
if cindy makes 7 of the shapes, how much fabric will cindy need, in square inches?

Explanation:

Step1: Find area of trapezoid in cm²

The formula for the area of a trapezoid is $A = \frac{(a + b)h}{2}$, where $a = 12$ cm, $b = 18$ cm, $h = 9$ cm.
Substitute values: $A = \frac{(12 + 18) \times 9}{2} = \frac{30 \times 9}{2} = 135$ cm².

Step2: Convert area to in² using scale

Scale: $1$ cm : $3$ in, so $1$ cm² : $3^2 = 9$ in² (since area scales with square of linear scale).
Area in in²: $135 \times 9 = 1215$ in² per shape.

Step3: Find total fabric for 7 shapes

Multiply per - shape area by 7: $1215 \times 7 = 8505$ in².

Answer:

8505