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Finding the Fourth Proportional to 643.98, 888.53 and 391.85

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Solution

The fourth proportional to 643.98, 888.53 and 391.85 is: 540.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.98 : 888.53 = 391.85 : x
  2. Step 2: Convert to fraction form
    643.98/888.53 = 391.85/x
  3. Step 3: Cross multiply
    643.98x = 888.53 × 391.85
  4. Step 4: Simplify right side
    643.98x = 348,167.02
  5. Step 5: Solve for x
    x = 348,167.02/643.98
  6. Step 6: Final answer
    x = 540.65

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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.