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Math worksheet focusing on identifying the constant of proportionality in various scenarios, including graphs, tables, and word problems.

A worksheet titled "Constant of Proportionality" with five problems, each containing a graph, table, or word problem to find the constant of proportionality, with one box in each row being the odd one out to be shaded.

A worksheet titled "Constant of Proportionality" with five problems, each containing a graph, table, or word problem to find the constant of proportionality, with one box in each row being the odd one out to be shaded.

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Show Answer Key & Explanations Step-by-step solution for: 20+ Grade 8 Constant of Proportionality Worksheets 2024
Let's solve each row of this "Odd Man Out" worksheet step by step. The goal is to:

1. Find the constant of proportionality (k) for each box.
2. Identify which box in each row does not match the others — that’s the “odd man out.”
3. Shade or mark the one that doesn’t belong.

---

🔹 Row 1


We have four boxes:

#### Box A: Graph
- Points: (1, 12), (2, 24), (3, 36)
- This is a straight line through origin → proportional.
- Constant of proportionality:
$ k = \frac{y}{x} = \frac{12}{1} = 12 $

So, k = 12

#### Box B: Word Problem – Jaylin’s Earnings
- $36 for 3 hours → $36 / 3 = $12/hour
- $60 for 5 hours → $60 / 5 = $12/hour
- So, rate = $12 per hour

k = 12

#### Box C: Table
| x | 12 | 24 | 60 |
|---|----|----|----|
| y | 1 | 2 | 5 |

Check ratios:
- 1/12 = 0.0833...
- 2/24 = 0.0833...
- 5/60 ≈ 0.0833...

All are equal: $ \frac{y}{x} = \frac{1}{12} $ → so k = 1/12

Wait! But earlier ones had k = 12. This is not the same.

Hold on — if k = y/x, then here k = 1/12, but others have k = 12.

So this one is different!

But let’s check again: Is it possible they meant k = x/y?

No — constant of proportionality is y = kx, so k = y/x.

Here:
- For x=12, y=1 → k = 1/12
- x=24, y=2 → k = 2/24 = 1/12
- x=60, y=5 → k = 5/60 = 1/12

So k = 1/12

But other boxes have k = 12

So this one is different.

#### Box D: Equation
- y = 12x → clearly k = 12

k = 12

---

Conclusion for Row 1:


- A: k = 12
- B: k = 12
- C: k = 1/12 ← ODD MAN OUT
- D: k = 12

➡️ Shade Box C (the table)

---

🔹 Row 2



#### Box A: Word Problem – Sophie’s Reading
- 4 books in 2 months → 4/2 = 2 books/month
- 10 books in 5 months → 10/5 = 2 books/month
→ Rate = 2 books per month

So, y = 2x → k = 2

But wait: Is it proportional? Yes, since rate is constant.

So k = 2

#### Box B: Table
| x | 0.1 | 2.6 | 15 |
|---|-----|-----|----|
| y | 0.1 | 2.6 | 15 |

Check ratios:
- 0.1 / 0.1 = 1
- 2.6 / 2.6 = 1
- 15 / 15 = 1

So k = 1

Wait — but we just said k = 2 from the word problem.

So this table has k = 1 → different.

But hold on — is the table consistent with y = x? Yes, because y = x → k = 1.

But the word problem has k = 2.

So conflict.

Wait — maybe I misread.

Let’s recheck:

- Sophie read 4 books in 2 months → 2 books/month → k = 2
- So if x = months, y = books → y = 2x → k = 2

But the table says: when x = 0.1, y = 0.1 → k = 1

So this table does NOT match.

So Box B is odd?

But let’s look at the rest.

#### Box C: Equation
- y = x → k = 1

k = 1

#### Box D: Graph
- Points: (1,1), (2,2), (3,3), (4,4), (5,5) → y = x → k = 1

k = 1

So:
- A: k = 2
- B: k = 1
- C: k = 1
- D: k = 1

So A is the odd one out

Because only A has k = 2, others have k = 1

➡️ Shade Box A (Sophie’s reading problem)

---

🔹 Row 3



#### Box A: Equation
- y = (1/3)x → k = 1/3

k = 1/3

#### Box B: Graph
- Points: (2,6), (4,12), (6,18), (8,24), (10,30)
- Check ratio: 6/2 = 3, 12/4 = 3, 18/6 = 3 → k = 3

So k = 3

But A has k = 1/3 → not matching

Wait — so already different.

Let’s continue.

#### Box C: Table
| x | 4 | 6 | 9 |
|---|---|---|---|
| y |12 |18 |27 |

Check:
- 12/4 = 3
- 18/6 = 3
- 27/9 = 3 → k = 3

k = 3

#### Box D: Word Problem – Alexis’ Cookies
- 24 cookies with 8 tsp sugar → 8/24 = 1/3 tsp per cookie
- 45 cookies with 15 tsp sugar → 15/45 = 1/3 tsp per cookie

So sugar per cookie = 1/3 → y = (1/3)x → k = 1/3

k = 1/3

So:
- A: k = 1/3
- B: k = 3
- C: k = 3
- D: k = 1/3

So two with k = 1/3 (A and D), two with k = 3 (B and C)

But the question says one odd man out.

Wait — perhaps I made a mistake.

Wait: In the graph, is it y = 3x or x = 3y?

Points: (2,6): y = 6, x = 2 → y = 3x → yes, k = 3

But the equation is y = (1/3)x → so k = 1/3

So:
- A: k = 1/3
- B: k = 3
- C: k = 3
- D: k = 1/3

So two groups: A and D → k = 1/3
B and C → k = 3

But only one should be odd.

Wait — unless I misread the graph.

Wait — the graph shows increasing values: (2,6), (4,12), etc. → y = 3x → k = 3

But A says y = (1/3)x → k = 1/3

So both A and D have k = 1/3, while B and C have k = 3

So which one is the odd one out?

Wait — maybe the equation is correct, and the graph is wrong?

No — the task is to find which one doesn't belong.

But there are two with k = 1/3 and two with k = 3.

But the instruction says: "there is an ODD MAN OUT" — meaning only one is different.

Hmm — contradiction.

Wait — let’s double-check the table.

Table: x=4, y=12 → y/x = 3
x=6, y=18 → 3
x=9, y=27 → 3 → k = 3

Graph: points show y = 3x → k = 3

Equation: y = (1/3)x → k = 1/3

Word problem: sugar per cookie = 1/3 → k = 1/3

So A and D have k = 1/3
B and C have k = 3

So no single odd one out?

But the problem says there is an odd man out.

Wait — maybe I misread the equation.

It says: y = 1/3x → which is y = (1/3)x → k = 1/3

But maybe the graph is actually inverse?

No — the graph clearly shows y increases faster than x.

(2,6): y = 3x → k = 3

But equation says k = 1/3 → so if y = (1/3)x, then when x=2, y=0.666... but graph shows y=6

So graph ≠ equation

So the equation is inconsistent with the graph.

But both the equation and word problem have k = 1/3

And graph and table have k = 3

So maybe the equation is the odd one?

Wait — no: the equation is y = 1/3x → k = 1/3

But the graph has k = 3 → so it's different.

But the word problem also has k = 1/3 → so it matches the equation.

So:
- A: y = (1/3)x → k = 1/3
- B: graph → k = 3
- C: table → k = 3
- D: word problem → k = 1/3

So A and D have k = 1/3
B and C have k = 3

So two pairs, but only one odd?

Wait — unless the graph is supposed to represent the same as the others?

But it clearly doesn’t.

Wait — maybe the equation is wrong?

Or maybe the table is wrong?

Wait — let’s look at the table:

x: 4, 6, 9
y: 12, 18, 27

This is y = 3x → k = 3

Graph: same → k = 3

Equation: y = (1/3)x → k = 1/3

Word problem: k = 1/3

So equation and word problem agree (k = 1/3)
graph and table agree (k = 3)

So both A and D are different from B and C.

But the problem says only one odd man out.

Unless I made a mistake in interpreting the word problem.

Alexis made 24 cookies with 8 tsp sugar → sugar per cookie = 8/24 = 1/3 tsp

45 cookies with 15 tsp → 15/45 = 1/3 tsp

So sugar per cookie = 1/3 → so if y = sugar, x = cookies → y = (1/3)x → k = 1/3

So correct.

Now, what about the equation? It says y = 1/3x → k = 1/3 → matches

But the graph shows y = 3x → k = 3 → does not match

The table shows y = 3x → k = 3 → does not match

So both graph and table have k = 3, while equation and word problem have k = 1/3

So either graph or table is the odd one, but they are the same.

Wait — maybe the graph is not showing y = 3x?

Let’s check the graph:

- x-axis: 2,4,6,8,10
- y-axis: 6,12,18,24,30
- Points: (2,6), (4,12), (6,18), (8,24), (10,30)

Yes → y = 3x → k = 3

So it's correct.

So the equation says y = (1/3)x → which would give (2, 0.666...) but graph shows (2,6)

So equation is wrong compared to the others.

But the word problem supports k = 1/3

So why is the equation labeled as y = 1/3x?

Wait — maybe the equation is the odd one out?

But it matches the word problem.

Unless the word problem is about cookies per sugar?

No — it says: "made 24 cookies with 8 tsp sugar"

So sugar used per cookie = 8/24 = 1/3 tsp

So if x = number of cookies, y = sugar → y = (1/3)x

So correct.

But the graph and table show y = 3x

So either the graph/table are wrong, or the equation/word problem are wrong.

But the equation and word problem both say k = 1/3

The graph and table both say k = 3

So two vs two — no odd one?

But the problem says one odd man out.

Wait — unless I misread the table.

Look at the table:

| x | 4 | 6 | 9 |
|---|---|---|---|
| y |12 |18 |27 |

Yes, y = 3x

But maybe it’s supposed to be x = 3y? No, that would be inverse.

Alternatively, maybe the constant of proportionality is defined as x/y?

No — standard is y = kx, so k = y/x

So k = 3 for table and graph

k = 1/3 for equation and word problem

So the equation and word problem are consistent, and graph and table are consistent

But only one should be odd.

Wait — maybe the equation is written incorrectly?

But it says: y = 1/3x → which is correct for the word problem.

But the graph and table are for a different scenario.

So perhaps the graph is the odd one?

But it matches the table.

Wait — unless the table is mislabeled?

No.

Wait — look at the graph: it goes from (2,6) to (10,30)

But the equation says y = (1/3)x → so at x=2, y=0.666...

But the graph shows y=6 → so it’s off by a factor of 9.

Wait — unless the graph is for x = (1/3)y?

Then y = 3x → which matches the graph.

So maybe the equation is wrong.

But it says y = 1/3x

But the word problem supports y = (1/3)x

So why is the graph showing y = 3x?

Unless the graph is for number of cookies vs sugar?

But it’s labeled as x and y, no units.

But in the table, it's x and y — no labels.

But the word problem is about sugar and cookies.

So likely, the equation and word problem are for sugar vs cookies → y = (1/3)x

The graph and table are for cookies vs sugar → y = 3x

So they are inverses.

But the constant of proportionality depends on how you define variables.

But in the table, it's x and y, and y = 3x → k = 3

In the equation, y = (1/3)x → k = 1/3

So they are different.

But the word problem supports k = 1/3

The graph and table support k = 3

So which one is the odd one?

But notice: the equation is labeled as y = 1/3x

The graph shows y = 3x

So the equation and the graph are inconsistent.

But the table also shows y = 3x

So equation is the only one with k = 1/3

But the word problem also has k = 1/3

So equation and word problem match

graph and table match

So two pairs

But the problem says one odd man out.

Wait — unless the table is the odd one?

Let’s check the table again.

x: 4, 6, 9
y: 12, 18, 27

Is this proportional? Yes, y = 3x

But look at the values: 4→12, 6→18, 9→27

But the word problem says: 24 cookies with 8 tsp sugar

So if x = sugar, y = cookies → then 8 tsp → 24 cookies → y = 3x → k = 3

Ah! Wait — maybe the word problem is about cookies per teaspoon of sugar?

Yes: 8 tsp → 24 cookies → 24/8 = 3 cookies per tsp

So y = 3x → k = 3

I think I flipped it!

Let’s re-read:

> "Alexis made 24 cookies with 8 teaspoons of sugar and 45 cookies with 15 teaspoons of sugar."

So cookies = y, sugar = x

Then:
- x = 8, y = 24 → y/x = 3
- x = 15, y = 45 → y/x = 3

So y = 3x → k = 3

Oh! I had it backward!

I thought y was sugar, but it's cookies = y, sugar = x

So k = 3

So k = 3

Similarly, the equation says y = (1/3)x → k = 1/3 → this is wrong

So now:
- A: y = (1/3)x → k = 1/3
- B: graph → y = 3x → k = 3
- C: table → y = 3x → k = 3
- D: word problem → y = 3x → k = 3

So only A has k = 1/3

Others have k = 3

➡️ Shade Box A (the equation y = 1/3x)

It's the odd one out.

---

🔹 Row 4



#### Box A: Word Problem – Jazmyn’s Paint
- 2 gallons for 5 walls → 2/5 = 0.4 gallons per wall
- 4 gallons for 10 walls → 4/10 = 0.4 gallons per wall
→ So constant: 0.4 gallons/wall

So k = 0.4 = 2/5

#### Box B: Table
| x | 0.5 | 1.5 | 3.5 |
|---|-----|-----|-----|
| y | 0.2 | 0.6 | 1.4 |

Check ratios:
- 0.2 / 0.5 = 0.4
- 0.6 / 1.5 = 0.4
- 1.4 / 3.5 = 0.4

So k = 0.4 = 2/5

k = 2/5

#### Box C: Graph
- Points: (2,5), (4,10), (6,15), (8,20), (10,25)
- y/x = 5/2 = 2.5, 10/4 = 2.5, etc. → k = 2.5 = 5/2

Wait — this is not 0.4

So k = 2.5

But others have k = 0.4

So this is different.

#### Box D: Equation
- y = 2/5x → k = 2/5 = 0.4

k = 0.4

So:
- A: k = 0.4
- B: k = 0.4
- C: k = 2.5
- D: k = 0.4

So C (graph) is the odd one out

➡️ Shade Box C (the graph)

---

🔹 Row 5



#### Box A: Table
| x | 1 | 2 | 3 |
|---|---|---|---|
| y |1.2|2.4|3.6|

Check:
- 1.2/1 = 1.2
- 2.4/2 = 1.2
- 3.6/3 = 1.2 → k = 1.2

But the equation says y = 1.25x → k = 1.25

So not matching.

But let’s see.

#### Box B: Equation
- y = 1.25x → k = 1.25

#### Box C: Word Problem – Grapes
- 4 lbs cost $5 → $5/4 = $1.25/lb
- 7 lbs cost $8.75 → $8.75/7 = ?
8.75 ÷ 7 = 1.25 → yes, $1.25 per pound

So k = 1.25

#### Box D: Graph
- Points: (4,5), (8,10), (12,15), (16,20), (20,25)
- y/x = 5/4 = 1.25, 10/8 = 1.25, etc. → k = 1.25

So:
- A: k = 1.2
- B: k = 1.25
- C: k = 1.25
- D: k = 1.25

So A (table) has k = 1.2, others have k = 1.25

➡️ Shade Box A (the table)

---

Final Answers:



| Row | Odd Man Out | Reason |
|-----|-------------|--------|
| 1 | Table (x,y) | k = 1/12 vs others k = 12 |
| 2 | Sophie’s reading | k = 2 vs others k = 1 |
| 3 | Equation y = 1/3x | k = 1/3 vs others k = 3 |
| 4 | Graph | k = 2.5 vs others k = 0.4 |
| 5 | Table (x,y) | k = 1.2 vs others k = 1.25 |

---

📌 Summary of Shading:


- Row 1: Shade the table (third box)
- Row 2: Shade the word problem (first box)
- Row 3: Shade the equation (first box)
- Row 4: Shade the graph (third box)
- Row 5: Shade the table (first box)

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Parent Tip: Review the logic above to help your child master the concept of constant of proportionality worksheet.
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