Practice Set · Part 1
Write and Represent Inequalities
Pick up where we left off
Where we left off
Our goal: I can write inequalities to represent real-world situations, explain what each part stands for, and build one for a situation I have not seen before.
The big idea: 'At least' means ≥ and 'at most' means ≤; 'more than' means > and 'fewer/less than' means < — and you can say why it is true, and where it would stop being true.
Model to copy — Watch me
- Clue: 'The suspect is at least 18 years old.'
- I let a stand for the age. 'At least 18' means 18 or more.
- 'At least' includes 18, so I use the symbol ≥.
- My inequality is a ≥ 18. So a could be 18, 19, 20, and up.
Start here
You did these with your group. Now do them on your own — the model above is yours to copy.
- 1
Same stepsFinish what the group started. Use the model above, step for step.
Try it together — then prove it: Clue: 'A bag holds fewer than 10 items.' What does 'fewer than' mean? It means less than, and it does NOT include 10, so we use <. We let n be the number of items: n < 10. Now prove it: say why that move had to work at all — not just that it did.Show your work - 2
Warm restartSolve: 6x = 42
- Ax = 48
- Bx = 36
- Cx = 7
- Dx = 252
How do you know?
- 3
Warm restartSolve: n / 3 = 8
- An = 11
- Bn = 5
- Cn = 3
- Dn = 24
How do you know?
- 4
Warm restartSolve: 9m = 63
- Am = 54
- Bm = 72
- Cm = 567
- Dm = 7
How do you know?
Practice Set · Part 2
Write and Represent Inequalities
Keep going
You answered these out loud. Now write them.
Answer, then say how you know — the reason is the part that counts.
- 5
Think it throughWhich speed is NOT possible for the getaway car?
- A70 mph
- B65 mph
- C60 mph
- D45 mph
Why is that the answer?
- 6
Think it throughDoes s ≤ 65 include 65 itself?
- AYes — the 'or equal to' part includes 65
- BNo — it must be strictly less
- COnly if the car stops
- DOnly on a highway
How do you know? Give a second reason as well.
- 7
Think it throughWhich inequality means 'at most 65'?
- As ≤ 65
- Bs < 65
- Cs ≥ 65
- Ds > 65
Explain your thinking. What would have to change for a different choice to be right?
- 8
Back to the modelHow do the words 'at least' and 'at most' change the inequality symbol compared to 'more than' and 'fewer than'?
Practice Set · Part 3
Write and Represent Inequalities
Words and reasoning
Word bank · Banco de palabras
Use the words
Fill each blank with a word from the bank.
- Use <, >, ≤ or ≥ when the answer is a ___ of values rather than one.
- A math sentence comparing values with <, >, ≤, or ≥ is an ___.
- The symbol > that means one value is larger than another means ___.
- The symbol < that means one value is smaller than another means ___.
Explain the thinking
- 9
Find the mistakeAnother student made this exact mistake in this lesson. Explain why it is wrong, then write what they should have done.
The mistake: A common mistake in Write Inequalities is using a strict symbol (> or <) for a phrase that actually includes the boundary value. - 10
Say moreHow do the phrases 'at least' and 'at most' change which inequality symbol you choose compared to 'more than' and 'fewer than'?
- 11
Write your ownWrite your own problem about this situation, then solve it and show the answer. The situation: Three balance scales are shown. On two of them the pans hang at different heights, so one side is heavier. On the third the pans are level.
Show your work
Practice Set · Part 4
Write and Represent Inequalities
Show what you know
Last check
These two come from Lesson 8.3. If they are shaky, that is the lesson to revisit — not this one.
- 12
Show what you knowExplain your thinking — Which inequality represents: 'A number n is at least 14'?
- An ≥ 14
- Bn > 14
- Cn ≤ 14
- Dn < 14
Explain your choice.
- 13
From Lesson 8.3Explain your thinking — Solve: w / 8 = 6
- Aw = 48
- Bw = 14
- Cw = 0.75
- Dw = 2
How do you know?
- 14
From Lesson 8.3Check: does 9 work?
- AYes — 7 × 9 = 63
- BNo — 7 × 9 = 56
- CNo — 7 + 9 = 16
- DOnly if kits cost $9
How do you know?
Be honest — this tells your teacher what to do next
| I can… | Not yet | Getting there | Got it |
|---|---|---|---|
| I can write inequalities to represent real-world situations, explain what each part stands for, and build one for a situation I have not seen before. | |||
| I can explain why it works: 'At least' means ≥ and 'at most' means ≤; 'more than' means > and 'fewer/less than' means <… | |||
| I can justify my answer to a skeptic and connect it to a second strategy or representation. |
One question I want to ask my group next time