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Finding the Fourth Proportional to 643.58, 887.91 and 391.42

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Solution

The fourth proportional to 643.58, 887.91 and 391.42 is: 540.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.58 : 887.91 = 391.42 : x
  2. Step 2: Convert to fraction form
    643.58/887.91 = 391.42/x
  3. Step 3: Cross multiply
    643.58x = 887.91 × 391.42
  4. Step 4: Simplify right side
    643.58x = 347,545.73
  5. Step 5: Solve for x
    x = 347,545.73/643.58
  6. Step 6: Final answer
    x = 540.02

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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.