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Finding the Fourth Proportional to 643.78, 888.15 and 381.79

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Solution

The fourth proportional to 643.78, 888.15 and 381.79 is: 526.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.78 : 888.15 = 381.79 : x
  2. Step 2: Convert to fraction form
    643.78/888.15 = 381.79/x
  3. Step 3: Cross multiply
    643.78x = 888.15 × 381.79
  4. Step 4: Simplify right side
    643.78x = 339,086.79
  5. Step 5: Solve for x
    x = 339,086.79/643.78
  6. Step 6: Final answer
    x = 526.71

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.