Bell Work Use a ratio table or set up a proportion to solve the proportion. A man rides his bike at a constant speed for 2 hours and travels 30 miles. If he were to continue riding at the same constant speed, how many miles would he travel in 5 hours? ANSWER 75 mi A teacher can grade 4 tests in 25 minutes. At this rate, how long will it take her to grade 36 tests? ANSWER 225 min If three bundles of shingles cover 75 square feet of a roof, how many bundles will it take to cover a roof that is 1800 square feet? ANSWER 72 bundles

Scale Drawings

Scale Drawing A scale drawing represents something that is too large or too small to be drawn at its actual size. Maps and blueprints are examples of scale drawings.

A scale drawing is a diagram of an object in which the dimensions are in proportion to the actual dimension of the object. The scale on a scale drawing tells how the drawing’s dimensions and the actual dimensions are related. The scale “1 in. : 12 ft.” means that for every 1 inch you have 12 feet.

Using the Scale of a Map centimeters kilometers On the map, the distance between China and New Sweden is 4.5 centimeters. Use the map of Maine to find the distance between the towns of China and New Sweden. Write and solve a proportion to find the distance between the towns. SOLUTION 1 65 4.5 d = centimeters kilometers d = 65 x 4.5 d = 292.5 The actual distance between China and New Sweden is about 292.5 kilometers. ANSWER

centimeters kilometers Use the map to find the distance (in kilometers) between Paris and Marshfield. On the map the distance between Paris and Marshfield is 3.85 centimeters. Write and solve a proportion to find the distance d between the towns. SOLUTION 1 65 3.85 d = centimeters kilometers 1d = 3.85 x 65 d = 250.25 The actual distance between Paris and Marshfield is about 250 kilometers. ANSWER

Scale Drawings Strawberry Point, Iowa, has a strawberry sculpture that is 15 feet tall. If the scale of this model is 10 feet to 1 inch. How tall was the original strawberry?

Solution H = 1.5 inches The original strawberry was 1.5 inches ANSWER

You try: Models of buildings in Boise, Idaho were created by using a scale of 1 in. : 45 ft. Find the height of the model in inches for the given height of the building. Marriott Hotel: 688.5 ft. = 15.3 inches Book Tower: 472.5 ft. = 10.5 inches

Finding the Scale Solution The model’s scale is 1:12 = = A museum is creating a full-size Tyrannosaurus Rex for a model. The model is 40 inches in length, from the nose to the tail. The resulting dinosaur will be 40 feet in length. What is the model’s scale? Solution Write a ratio. Make sure that both measures are in inches. Then simplify the fraction. The model’s scale is 1:12 scale model = = full size

You Try: A craftsman makes miniature replicas of Victorian furniture. The scale model of a table that he made is 3 inches long. The full-size table is 39 inches long. What is the model’s scale? simplify 3 is the greatest common factor of 3 and 36 - divide each by 3 = 1:13

1) Find the scale factor of the blueprint of a school bus parking lot if the scale is written as 1 inch = 8 feet 2) On a scale drawing of a new classroom, the scale is 1 centimeter = 2.5 meters. What is the scale factor? 1 in : 8 ft (with units) 1:96 (without units) 1 cm : 2.5 m (with units) 1: 250 (without units)

Practice: Scale Drawing worksheet