A rectangle has dimensions \(4\) in by \(6\) in at a scale of \(1\) in \(:2\) ft. If redrawn at a new scale of \(1\) in \(:4\) ft, what are the new dimensions?
- \(1\) in by \(1.5\) in
- \(2\) in by \(3\) in
- \(8\) in by \(12\) in
- \(16\) in by \(24\) in
Students will build Grade 7 mastery of reproducing scale drawings at a different scale using models, equations, and test-style reasoning.
A rectangle has dimensions \(4\) in by \(6\) in at a scale of \(1\) in \(:2\) ft. If redrawn at a new scale of \(1\) in \(:4\) ft, what are the new dimensions?
A blueprint shows a room measuring \(3\) cm by \(5\) cm at a scale of \(1\) cm \(:1\) m. What are the actual room dimensions?
A scale model of a car is drawn at a scale of \(1\) in \(:5\) ft. If the model is \(8\) inches long, what is the length of the actual car?
A rectangle on a map has length \(7\) cm and width \(4\) cm. The map scale is \(1\) cm \(:2\) km. When the map is enlarged so that the new scale becomes \(1\) cm \(:1\) km, what are the new dimensions?
A floor plan shows a rectangular office that is \(2.5\) inches by \(3.5\) inches at a scale of \(1\) in \(:10\) ft. Which pair of measurements are the actual office dimensions?
A scale drawing of a rectangular garden is \(6\) cm long at a scale of \(1\) cm \(:0.5\) m. If the scale is changed to \(1\) cm \(:1\) m, what will be the new length?
A blueprint of a house wing shows a rectangular area \(5\) cm by \(7\) cm at scale \(1\) cm \(:3\) m. A new blueprint is drawn at scale \(1\) cm \(:6\) m. What are the dimensions on the new blueprint?
A landscape drawing shows a rectangular flower bed \(8\) inches by \(12\) inches at scale \(1\) in \(:2\) ft. What are the dimensions of the actual flower bed?
At scale 1:2, the drawing is \(4 \times 6\) in representing a fixed real object. At scale 1:4, the same object is represented differently. The ratio of real-world per drawing unit goes from 2 to 4 (doubled), so the drawing must shrink by factor \(4 \div 2 = 2\). New dimensions: \(4 \div 2 = 2\) in and \(6 \div 2 = 3\) in.
Scale 1 cm : 1 m means 1 cm on the drawing represents 1 m in reality. Scale factor is 1 m per cm. Multiply each drawing dimension by the scale factor: \(3 \text{ cm} \times 1 \text{ m/cm} = 3\) m and \(5 \text{ cm} \times 1 \text{ m/cm} = 5\) m. This foundational skill (single scale) is the basis for comparing two scales in later problems.
Scale 1 in : 5 ft means 1 inch on the model represents 5 feet in reality. Scale factor is 5 ft per inch. To find actual length, multiply: \(8 \text{ in} \times 5 \text{ ft/in} = 40\) ft. The scale factor (5 ft/in) is the key ratio that converts drawing dimensions to real-world dimensions.
Original scale 1:2 means 1 cm = 2 km. New scale 1:1 means 1 cm = 1 km. The real-world distance per cm is halved, so the drawing must double in size. Scale factor ratio: \(1 \div 2 = 0.5\), reciprocal shrink \(= 2\). New dimensions: \(7 \times 2 = 14\) cm and \(4 \times 2 = 8\) cm.
Multiply drawing dimensions by scale factor: \(2.5 \times 10 = 25\) ft and \(3.5 \times 10 = 35\) ft.
Original scale 1:0.5 means 1 cm = 0.5 m. New scale 1:1 means 1 cm = 1 m. Real-world distance per cm doubled (0.5 to 1), so the drawing shrinks. Scale factor ratio: \(1 \div 0.5 = 2\), so drawing shrinks by factor \(1 \div 2 = 0.5\). New length: \(6 \times 0.5 = 3\) cm (or \(6 \div 2 = 3\) cm).
Original scale 1:3 means 1 cm = 3 m. New scale 1:6 means 1 cm = 6 m. Real-world distance per cm doubled (3 to 6), so drawing shrinks by factor \(3 \div 6 = 0.5\) (or multiply by reciprocal 6 รท 3 = 2, then invert: 1/2). New dimensions: \(5 \div 2 = 2.5\) cm and \(7 \div 2 = 3.5\) cm.
Multiply by scale factor: \(8 \text{ in} \times 2 \text{ ft/in} = 16\) ft and \(12 \times 2 = 24\) ft.