Input any three values among \( A, B, C, \) or \( D \), and quickly calculate the missing value that satisfies the proportional relationship \( A : B = C : D \).
Calculate the Fourth Value A : B = C : D
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Result
What Is a Proportional Relationship?
In mathematics, a proportion represents the equality of two ratios. If \( A : B = C : D \), it implies:
\( \frac{A}{B} = \frac{C}{D} \)
Using the cross-multiplication principle, we get:
\( A \times D = B \times C \)
This relationship allows us to calculate the fourth value when three values are known.
How to Calculate the Fourth Value?
Using the proportional formula \( A : B = C : D \):
If \( A, B, \) and \( C \) are known, \( D \) can be calculated as: \( D = \frac{B \times C}{A} \).
If \( B, C, \) and \( D \) are known, \( A \) can be calculated as: \( A = \frac{B \times C}{D} \).
If \( A, C, \) and \( D \) are known, \( B \) can be calculated as: \( B = \frac{A \times D}{C} \).
If \( A, B, \) and \( D \) are known, \( C \) can be calculated as: \( C = \frac{A \times D}{B} \).
Examples
Example 1: Given \( A = 3 \), \( B = 4 \), and \( C = 9 \), find \( D \).