3.1 Small Group · Group 1
Second Practice Form · Re-Teach, Homework or Retake · Same Standard, New Problems
Understand Ratios · Ratio · Procedural Fluency · Real-World Applications
- A ratio compares two amounts. It tells how much of one thing there is for another thing. We'll walk through a worked example, try one together, then you'll try a few with hints right there when you need them.
- Chef Reyes uses 3 cups of apple juice for every 2 cups of sparkling water.
- I am comparing two amounts: apple juice and sparkling water.
- I write apple juice to sparkling water, in that order, as 3 to 2, or 3:2.
- I can also draw the ratio. On a tape diagram I give apple juice 3 equal parts and sparkling water 2 equal parts, so one batch is 5 parts in all.
- Those same 5 parts show a second ratio: apple juice to the whole fruit drink is 3 to 5.
- On a double number line I line the two amounts up: 5 cups of fruit drink pairs with 3 cups of apple juice, and 10 cups of fruit drink pairs with 6 cups of apple juice.
- Understand Ratios (Comprender razones) — Use a ratio to compare two quantities by division.
- Ratio (Razón) — A way to compare two amounts, like 3 to 2.
- Comparison (Comparación) — Looking at two or more amounts to see how they are related.
- Part-to-part (Parte a parte) — A ratio comparing one part of a group to another part.
- Part-to-whole (Parte a todo) — A ratio comparing one part to the whole group.
- Colon notation (Notación con dos puntos) — Writing a ratio with two dots between the numbers, like 3:2.
- A common mistake in Understand Ratios is writing the ratio in the wrong order: when asked for the ratio of apple juice to sparkling water in a recipe that uses 3 cups of apple juice for every 2 cups of sparkling water, some students write 2:3 (sparkling water to apple juice) because they list the ingredients in whatever order comes to mind rather than the order the question asks for. The two ratios describe different drinks — 3:2 means 3 cups of juice for every 2 cups of water, while 2:3 would mean only 2 cups of juice for every 3 cups of water. Always match the order of your ratio to the order named in the question: "apple juice to sparkling water" means the apple juice number comes first, giving 3:2.
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1 MULTIPLE CHOICE
A fruit salad has 5 pieces of melon, 3 pieces of pineapple, and 2 grapes. What is the ratio of pineapple to melon?
- A3:5
- B5:3
- C3:10
- D3:2
✏️ Workspace & Solution Steps -
2 MULTIPLE CHOICE
A parking lot has 10 cars and 6 trucks. What is the part-to-whole ratio of trucks to total vehicles?
- A6:16
- B10:6
- C6:10
- D16:6
✏️ Workspace & Solution Steps -
3 MULTIPLE CHOICE
Prep Bowl A: Chef Reyes stirs 7 cups of flour with 4 cups of water to make dough. What is the part-to-part ratio of flour to water?
- A7:4
- B4:7
- C7:11
- D11:4
✏️ Workspace & Solution Steps -
4 MULTIPLE CHOICE
A class has 5 chefs and 7 helpers (12 total). What is the part-to-whole ratio of chefs to the whole class?
- A5:12
- B5:7
- C7:12
- D12:5
✏️ Workspace & Solution Steps
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5 ERROR ANALYSIS
Spot the Mistake — Order of a Ratio
- 1Read the problem:A salad bar has 5 bowls of soup and 8 sandwiches. Write the ratio of soup to sandwiches.
- 2Identify the amounts:Soup = 5 and sandwiches = 8.
- 3Write the ratio:A student writes the ratio of soup to sandwiches as 8:5.
- 4Answer:The ratio of soup to sandwiches is 8:5.
Which step contains the error? Explain the mathematical misconception and write the correct calculation below.
✏️ Corrected Mathematical Work & Explanation -
6 ERROR ANALYSIS
Spot the Mistake — Part-to-Whole Ratio
- 1Read the problem:A class has 9 boys and 6 girls. Write the part-to-whole ratio of girls to the whole class.
- 2Count the whole:9 + 6 = 15 students in all.
- 3Write the ratio:A student writes girls to the whole class as 6:9.
- 4Answer:The part-to-whole ratio of girls to the whole class is 6:9.
Which step contains the error? Explain the mathematical misconception and write the correct calculation below.
✏️ Corrected Mathematical Work & Explanation
Writing Task: Justify why your mathematical solution is accurate and complete.