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Section 1.4 . Ratios & Proportions. Ratios. A ratio is a comparison of two numbers that can be written in three different ways For example, if the student to faculty ratio at a certain college is 40 to 1, the ratio can also be expressed as 40:1 or as .
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Section 1.4 Ratios & Proportions
Ratios • A ratio is a comparison of two numbers that can be written in three different ways • For example, if the student to faculty ratio at a certain college is 40 to 1, the ratio can also be expressed as 40:1 or as . • This means that four every one faculty member, there are 40 students.
Rates • When the quantities being compared in a ratio have different units, the ratio is called a rate. • For example: the rate 30 mpg (miles per gallon) is a comparison of the two quantities 30 miles and 1 gallon. The rate could have been written as .
Exercise 1 A juice drink recipe calls for 3 parts orange juice and 2 parts pineapple juice. Which of the following statements are correct. • For every cup of pineapple juice, you need 1.5 cups of orange juice. • For every two quarts of pineapple juice you need 6 quarts of orange juice. • When the juices are mixed, the mixture is orange juice. • The ratio of pineapple juice to orange juice is 2:3. • If you have 15 oz. of orange juice, you need to add 10 oz. of pineapple juice.
Proportions • When two ratios are equal, they form a proportion. • When two ratios are equal, the quantities being compared are in proportion with each other or just proportional. • For example: 30 mpg
Exercise 2 Complete the following ratios:
Exercise 2 Complete the following ratios: * ½ * 3 * ½ * 3
Exercise 3 If a school has 70 computers in the ratio of 3 desktops for every 4 laptops, how many of the computers are desktops?
Exercise 3 If a school has 70 computers in the ratio of 3 desktops for every 4 laptops, how many of the computers are desktops? 3 desktops : 4 laptops means 3 desktops : 7 computers 3 desktops : 7 computers means 30 desktops : 70 computers
Exercise 4a The racial composition in a Texas town is shown in the table below: A local university has 20250 total students. How many of them would need to be Hispanic so that the Hispanic students have a proportional representation at the University?
Exercise 4a The racial composition in a Texas town is shown in the table below: A local university has 20250 total students. How many of them would need to be Hispanic so that the Hispanic students have a proportional representation at the University?
Exercise 4b The racial composition in a Texas town is shown in the table below: Another local university has 2450 Black students. How many total students are needed so that the Black students have a proportional representation at the University?
Exercise 4b The racial composition in a Texas town is shown in the table below: Another local university has 2450 Black students. How many total students are needed so that the Black students have a proportional representation at the University?