Ratios Fractions and Percents A ratio is

Ratios, Fractions, and Percents • A ratio is sometimes a part-to-part comparison of two numbers measured in the same units. A bag contains 6 yellow marbles, 3 red marbles, 5 green marbles, and 4 blue marbles. • The Ratio of Red marbles to Blue marbles is 3 to 4, 3: 4, ¾. 1

Ratios, Fractions, and Percents • A ratio is sometimes a part-to-part comparison of two numbers measured in the same units. A bag contains 6 yellow marbles, 3 red marbles, 5 green marbles, and 4 blue marbles. • The Ratio of Red marbles to Blue marbles is 3 to 4, 3: 4, ¾. 2

5 yellow, 3 red, 5 green, 4 blue What is the ratio of yellow to red marbles? What is the ratio of blue to green marbles? A fraction is a part-to-whole comparison. A percent is also a part-to-whole comparison. What fraction of the bag is red? What percent of the bag is red? What fraction of the bag is blue? What percent of the bag is blue? 3

RATES • A rate is a comparison of two quantities measured in different units. • Suppose you read 230 words in two minutes, your reading rate would be 230 words 2 mins 4

Unit Rates • A unit rate is a rate that has a denominator of one. words 230 =÷ 2 115 words ÷ 2 minutes 2 1 minute • The unit rate is 115 words/min (115 words per minute) • To find Unit Rates divide the numerator by the denominator. Find the unit rate a. ) travel 1, 200 miles in 4 hours b. ) score 98 points in 6 games c. ) write 11 pages in 2 hours d. ) run 400 meters in 1 min 30 seconds 5

Unit Rates cont. • • • The comparisons: “ 45 miles per gallon, ” “$3. 50 per hour, ” “ 8. 5 kilometers per hour, ” and “two sandwiches for each person, ” are all unit rates. • “Per gallon” means “for one gallon” and “Per hour” means “for one hour. ” 6

Unit Price • A unit price is the price per unit of an item. (The price for 1. ) • To find the unit price, divide the price by the size of the item. • Find the unit price: a. ) $12 for 4 yd b. ) $9 for 5 fl oz c. ) 4 m for $10 d. ) 20 lbs for $7 7

Determining the Better Buy • To determine the better buy find each unit price then compare them. Find each unit price. Then determine the better buy. 1. detergent: 2. ribbon: 1 yd for $. 49 3 yd for $1. 95 3. popcorn: 15 oz for $1. 69 30 oz for $2. 99 32 fl oz for $1. 99 50 fl oz for $2. 49 8

• A proportion is an equation that states two ratios are equal. • In the proportion 6 = 12 8 16 The products 6● 16 and 8● 12 are called cross products. • If two ratios form a proportion, their cross products are EQUAL. Which pairs of ratios form a proportion? a. )3 , 6 b. )6 , 4 c. )4 , 5 d. )6 , 9 8 16 9 6 8 9 10 15 9

Maps and Scale Drawings • A scale drawing is an enlarged or reduced drawing of an object. • You use a map’s scale and proportions to find actual distances. • The scale of a map is 2 cm = 15 km. Find the actual distance for the following map distances. a. )8 cm b. )1. 3 cm c. )15. 5 cm *d. ) 5 mm 10