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Finding the Fourth Proportional to 643.78, 966.14 and 438.56

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Solution

The fourth proportional to 643.78, 966.14 and 438.56 is: 658.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.78 : 966.14 = 438.56 : x
  2. Step 2: Convert to fraction form
    643.78/966.14 = 438.56/x
  3. Step 3: Cross multiply
    643.78x = 966.14 × 438.56
  4. Step 4: Simplify right side
    643.78x = 423,710.36
  5. Step 5: Solve for x
    x = 423,710.36/643.78
  6. Step 6: Final answer
    x = 658.16

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.