ratios and word problems with ratios. skill maintenance page 55
DESCRIPTION
Commutative Property Addition = = Multiplication 3 * 4 = 4 * 3 2 * 7 * 8 = 8 * 2 * 7TRANSCRIPT
Ratiosand
Word Problems with Ratios
Skill MaintenancePage 55
Commutative Property
• Addition 3 + 4 = 4 + 3 5 + 17 + 43 = 17 + 43 + 5
• Multiplication 3 * 4 = 4 * 3 2 * 7 * 8 = 8 * 2 * 7
Substitution
• Important concept when working with variables
• Substitution: Replace a variable with a number value
Ratios
• Ratio: Compares two numbers• We can write a ratio as
–1 to 3–1:3–1/3
We often use ratios in cooking. A recipe calls for one cup of sugar and two cups of flour. The ratio of sugar to flour is
one to two.
We can also use ratios in painting. Let’s say we need to mix three cans of blue paint and one can of white. The ratio
of blue to white is three to one.
We might use ratios to make comparisons in the classroom Let’s say there are six boys and eighteen girls in the class.
The ratio of boys to girls is six to eighteen.
Why can’t we call them fractions?
• A ratio can:– Represent a part-to-whole relationship– Describe two parts of a whole relationship
• Fraction is a special type of ratio (part-to-whole)
Ratio Examples
Ratio Examples
Ratio Examples
Ratio Examples
Ratio Examples
Ratios
• Fractions are always part-to-whole relationships.
• Ratios may be part-to-whole relationships OR they can be part-to-part relationships.
Group Card Activity
Group Card Activity• Write the following ratios in two ways and
tells us if it is a part-to-part or part-to-whole ratio:– Hearts to Diamonds– Spades to all cards– Face cards to Non-face cards– Odd numbered cards to all cards– Make up two of your own
• One part-to-whole• One part-to-part
Word Problems Using Ratios
• Break Problem into small steps• Step 1: Label the ratio we are looking for• Step 2: Think about the numbers for our
ratio.• Step 3: Use the numbers we found to set
up the ratio.
Problem-Solving ActivityPage 57
HomeworkPages 147 and 148
All ActivitiesAll Problems