Let's solve each of the proportion problems step by step. A
proportion is a statement that two ratios are equal. To check if two ratios form a proportion, we can use
cross-multiplication:
If $\frac{a}{b} = \frac{c}{d}$, then $a \times d = b \times c$. If the cross products are equal, the ratios form a proportion.
---
Problem 1: Is this a proportion?
$$
\frac{1}{4} = \frac{8}{32}
$$
Step 1: Cross-multiply:
$1 \times 32 = 32$
$4 \times 8 = 32$
Since $32 = 32$, the cross products are equal.
✔ Yes, this is a proportion.
---
Problem 2: Is this a proportion?
$$
\frac{25}{40} = \frac{15}{24}
$$
Step 1: Cross-multiply:
$25 \times 24 = 600$
$40 \times 15 = 600$
Since $600 = 600$, the cross products are equal.
✔ Yes, this is a proportion.
---
Problem 3: Is this a proportion?
$$
\frac{3}{5} = \frac{23}{25}
$$
Step 1: Cross-multiply:
$3 \times 25 = 75$
$5 \times 23 = 115$
Since $75 \neq 115$, the cross products are not equal.
✘ No, this is
not a proportion.
---
Problem 4: Is this a proportion?
$$
\frac{6}{72} = \frac{10}{120}
$$
Step 1: Cross-multiply:
$6 \times 120 = 720$
$72 \times 10 = 720$
Since $720 = 720$, the cross products are equal.
✔ Yes, this is a proportion.
---
Problem 5: Is this a proportion?
$$
\frac{9}{12} = \frac{2}{4}
$$
Step 1: Cross-multiply:
$9 \times 4 = 36$
$12 \times 2 = 24$
Since $36 \neq 24$, the cross products are not equal.
✘ No, this is
not a proportion.
---
✔ Final Answers:
1.
YES – $\frac{1}{4} = \frac{8}{32}$ → Proportion
2.
YES – $\frac{25}{40} = \frac{15}{24}$ → Proportion
3.
NO – $\frac{3}{5} = \frac{23}{25}$ → Not a proportion
4.
YES – $\frac{6}{72} = \frac{10}{120}$ → Proportion
5.
NO – $\frac{9}{12} = \frac{2}{4}$ → Not a proportion
---
💡 Explanation Summary:
To determine if two ratios form a proportion:
- Use
cross multiplication.
- If the products are equal → it's a proportion.
- If not → it's not a proportion.
You can also simplify fractions to check:
- For example, $\frac{1}{4} = \frac{8}{32}$ because both simplify to $0.25$.
- But $\frac{3}{5} = 0.6$, and $\frac{23}{25} = 0.92$ → not equal.
This method works every time!
Let me know if you'd like a printable version or explanation for students! 😊
Parent Tip: Review the logic above to help your child master the concept of proportional or not worksheet.