Computing Actual Lengths From a Scale Drawing

Learning Target

• I can compute actual lengths in a picture using the scale.

Find the length and the width of the basketball court based on the drawing.

Find the width of the court.

Find the scale factor. Scale factor: scale = Actual

1 in =15 ft

1 in =15 ft *12 in

Scale Factor1 in 180 in

Use a proportion.1 in = 2 in. 15 ft x

Cross Multiply1x = 15 * 2 x = 30 ft.Width= 30 ft

Find the length the court. Use a proportion. Convert the mixed number to a fraction first.1 in = in. 15 ft x

Cross Multiply1x = 15 * x = Length= 25 ft.

Find the length. 1 cm = 20 meters 8 cm x 20 meters = 160 meters

Find the width. 1 cm = 20 meters 4 cm x 20 meters = 80 meters

1 1/8 in.

1 ½ in.

Find the width. Use the scale factor in a proportion. Convert the mixed number to a fraction first.0.25 in. = 9/8 in. 1 in. x

Cross Multiply.25x = 1 * .25x= x= Change .25 to a fraction¼ x=9/8 Divide both sides by ¼ ¼ ¼ x = * Multiply by reciprocalx = x = 4.5 inches

1 1/8 in.

1 ½ in.

Find the length. Use the scale factor in a proportion. Convert the mixed number to a fraction first.0.25 in. = in. 1 in. x

Cross Multiply.25x = 1 * .25x= x= Change .25 to a fraction¼ x= Divide both sides by ¼ ¼ ¼ x = 3/2 * 4/1 Multiply by reciprocalx = 12/2x = 6 inches