Presentation on theme: "By Mrs. Pearson. I have a photo of my daughter Sarah and I want to enlarge it and make it into a poster. The photo is 4 inches by 6 inches. The poster."— Presentation transcript:
By Mrs. Pearson
I have a photo of my daughter Sarah and I want to enlarge it and make it into a poster. The photo is 4 inches by 6 inches. The poster maker uses a scale factor of. I want to find out what size the poster will be. 5151 Think: poster photo = 5151 l4l4 = 5151 1*l = 4*5 l = 20 Write a proportion to find the length l and one for the width w. Find the cross products. w6w6 = 5151 1*w = 6*5 w = 30 The poster will be 20 in. long and 30 in. wide.
We are taking a field trip to Pittsburg. On a road map, the distance between Philadelphia and Pittsburgh is 7.5 inches. What is the actual distance between the cities if the map scale is 1.5 inches = 60 miles? Let d be the actual distance between the cities. 1.5 60 = 7.5 d 1.5 · d = 60 · 7.5 1.5d = 450 1.5d 1.5 = 450 1.5 d = 300 The distance between the cities is 300 miles. Write a proportion. Find the cross products. Multiply. Divide both sides by 1.5.
If we drive at a rate of 60 miles per hour, how long will it take us to get to Pittsburg? Let t be the time it will take for us to travel. 60 miles 1 hour = 300 miles t hours 60· t = 1 · 300 60d = 300 60d 60 = 300 60 d = 5 It will take us 5 hours to travel between the cities. Write a proportion. Find the cross products. Multiply. Divide both sides by 60.