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Finding the Fourth Proportional to 429.29, 643.98 and 140.72

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Solution

The fourth proportional to 429.29, 643.98 and 140.72 is: 211.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    429.29 : 643.98 = 140.72 : x
  2. Step 2: Convert to fraction form
    429.29/643.98 = 140.72/x
  3. Step 3: Cross multiply
    429.29x = 643.98 × 140.72
  4. Step 4: Simplify right side
    429.29x = 90,617.65
  5. Step 5: Solve for x
    x = 90,617.65/429.29
  6. Step 6: Final answer
    x = 211.09

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.