āˆ Proportion Calculator

Solve: A/B = C/D ā€” Enter 3 known values, leave the unknown as empty.

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Solution

What is Proportion?

A proportion states that two ratios are equal: A/B = C/D. To find the missing value, use cross-multiplication.

A/B = C/D
Cross multiply: A Ɨ D = B Ɨ C
If D is unknown: D = (B Ɨ C) / A

Real-World Examples

  • Cooking: If 2 cups make 4 servings, how many cups for 10 servings?
  • Maps: If 1 inch = 50 miles, 3 inches = how many miles?
  • Pricing: If 5 apples cost $3, how much do 8 apples cost?

Frequently Asked Questions

How do you solve a proportion? ā–¼
Use cross-multiplication. For A/B = C/D: multiply diagonally to get AƗD = BƗC. Then solve for the unknown variable.
What is the difference between ratio and proportion? ā–¼
A ratio compares two quantities (e.g., 3:4). A proportion is an equation stating two ratios are equal (e.g., 3/4 = 6/8).
What does 'direct proportion' mean? ā–¼
In direct proportion, as one quantity increases, the other increases by the same factor. For example, if speed doubles, distance covered in same time doubles.