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Finding the Fourth Proportional to 429.38, 643.94 and 140.75

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Solution

The fourth proportional to 429.38, 643.94 and 140.75 is: 211.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    429.38 : 643.94 = 140.75 : x
  2. Step 2: Convert to fraction form
    429.38/643.94 = 140.75/x
  3. Step 3: Cross multiply
    429.38x = 643.94 × 140.75
  4. Step 4: Simplify right side
    429.38x = 90,633.85
  5. Step 5: Solve for x
    x = 90,633.85/429.38
  6. Step 6: Final answer
    x = 211.08

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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.