Lesson 3 Proportionality Ratios

Warm-Up Convert each fraction to a decimal. Convert each decimal to a fraction. 0.1 0.65 Complete the conversion: 30 centimeters = _____ millimeters

Target: Simplify and write ratios in three forms.

Vocabulary Ratio: A comparison of two numbers using division.

Writing Ratios A ratio comparing two numbers a and b can be written in one of three forms. OR a :b OR a to b A ratio should always be written in simplest form.

Example 1 Write a ratio each of three ways comparing: a. Julius’ number of green jelly beans to his total number of jelly beans. b. Luke’s number of green jelly beans to his total number of jelly beans. Fraction Colon “To” a. 1 : 4 1 to 4 b. 1 : 3 1 to 3

Example 2 Write a ratio for the number of red jelly beans Julius grabbed to the number of red jelly beans Luke grabbed. Write a ratio as a fraction and simplify. This ratio can also be written 2 : 1 or 2 to 1.

Example 3a Every day after school Kay and Trudy talk on their cell phones to each other. Write a ratio comparing the amount of time Kay spoke to the amount of time Trudy spoke during each conversation. On Monday, Kay spoke for 45 minutes and Trudy spoke for 30 minutes.

Example 3b Every day after school Kay and Trudy talk on their cell phones to each other. Write a ratio comparing the amount of time Kay spoke to the amount of time Trudy spoke during each conversation. On Tuesday, Kay spoke for 30 minutes and Trudy spoke for 1 hour. 1 hour = 60 minutes

Exit Problems Simplify the ratio 12 : 8 and write the ratio in all three forms. Nine out of 15 soccer players wore headbands on the field. Write the ratio of soccer players who wore headbands to total soccer players. Write the ratio of soccer players who did not wear headbands to total soccer players. Write the ratio of soccer players who wore headbands to those who did not wear headbands.

Communication Prompt What has a ratio of 1 : 1 in your life?