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Finding the Fourth Proportional to 643.29, 887.76 and 391.17

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Solution

The fourth proportional to 643.29, 887.76 and 391.17 is: 539.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.29 : 887.76 = 391.17 : x
  2. Step 2: Convert to fraction form
    643.29/887.76 = 391.17/x
  3. Step 3: Cross multiply
    643.29x = 887.76 × 391.17
  4. Step 4: Simplify right side
    643.29x = 347,265.08
  5. Step 5: Solve for x
    x = 347,265.08/643.29
  6. Step 6: Final answer
    x = 539.83

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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.