# RATIO AND PROPORTION A RATIO IS A COMPARISON

• Slides: 17

RATIO AND PROPORTION

A RATIO IS A COMPARISON OF TWO OR MORE NUMBERS There are several ways in which ratios may be written. Ratios may be written using • A colon : Example: 3: 6 – the is read as “ the ratios 3 to 6” • A fraction bar / Example: 3/6 – the is read as “ the ratios 3 to 6” • In words Example: 3 to 6

RATIO AS A COMPARISON OF TWO NUMBERS Lets see where we have used ratio before Paul made 3 tables in 6 days. The ration of tables made compared to days taken is 3 to 6

WELCOME TO BOBO’S NIGHT SCHOOL There are 8 boys and 4 girls in Bobo’s Night School. Total Number of individuals at Bobo’s Night School is? 1. What is the ratio of girls to boys using a fraction? 2. What is the ratio of girls to children in Bobo’s Night School (use a colon)? 3. What is the ratio of boys to children in Grant School (use words)?

WELCOME TO BOBO’S NIGHT SCHOOL There are 8 boys and 4 girls in Bobo’s Night School. Total Number of individuals at Bobo’s Night School is 12 1. What is the ratio of girls to boys using a fraction? 2. What is the ratio of girls to children in Bobo’s Night School (use a colon)? 3. What is the ratio of boys to children in Grant School (use words)? 4: 12 4 to 12

A PROPORTION IS A STATEMENT THAT TWO RATIOS ARE EQUAL. A proportion is an equation with a ratio on each side. 3/4 = 6/8 is an example of a proportion. The two statements are equal because if you simplify 6/8 we get 3/4, therefore both are equal.

A PROPORTION IS A STATEMENT THAT TWO RATIOS ARE EQUAL. A proportion is an equation with a ratio on each side. 1 3 = 4 12 is an example of a proportion. 3 1 The two statements are equal because if you simplify, we get 4 12 both are equal. , therefore

PROPORTIONS • Another way to check if proportions are equal is to cross multiply. Cross Multiply Both sides are equal therefor we say they are proportional proportion.

SOLVING PROPORTION PROBLEMS • When one of the four numbers in a proportion is unknown we can use the method of cross multiplication to solve for this unknown. This is called solving the proportion. • Letters are frequently used in place of the unknown number. (X)

SOLVING PROPORTION PROBLEMS • When one of the four numbers in a proportion is unknown we can use the method of cross multiplication to solve for this unknown. This is called solving the proportion. • Letters are frequently used in place of the unknown number. (X)

RATIOS & PROPORTIONS Solve the proportion: Cross multiply Simplify Solution for unknown

RATIOS & PROPORTIONS Solve the following proportions for x.

RATIOS & PROPORTIONS Solve the following proportions for x.

RATIOS & PROPORTIONS Solve the following proportions for x.

SCALE MEASUREMENT USING PROPORTIONS 1 cm = 5 m is a scale for a house plan. The actual length a wall is 70 m. What is the scale length of the wall? Cross multiply. Simplify Scale length of wall

SCALE MEASUREMENT USING PROPORTIONS A ratio of half bag of cement to 3 buckets of sand is used by a mason to render a wall. If he has 10 buckets of sand how much cement will he need? Cross multiply. Simplify Solution

SCALE MEASUREMENT USING PROPORTIONS A ratio of half bag of cement to 3 buckets of sand is used by a mason to render a wall. If he has 10 buckets of sand how much cement will he need? Cross multiply. Simplify Solution