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Finding the Fourth Proportional to 643.86, 888.57 and 381.78

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Solution

The fourth proportional to 643.86, 888.57 and 381.78 is: 526.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.86 : 888.57 = 381.78 : x
  2. Step 2: Convert to fraction form
    643.86/888.57 = 381.78/x
  3. Step 3: Cross multiply
    643.86x = 888.57 × 381.78
  4. Step 4: Simplify right side
    643.86x = 339,238.25
  5. Step 5: Solve for x
    x = 339,238.25/643.86
  6. Step 6: Final answer
    x = 526.88

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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.