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Finding the Fourth Proportional to 429.90, 644.40 and 213.36

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Solution

The fourth proportional to 429.90, 644.40 and 213.36 is: 319.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    429.90 : 644.40 = 213.36 : x
  2. Step 2: Convert to fraction form
    429.90/644.40 = 213.36/x
  3. Step 3: Cross multiply
    429.90x = 644.40 × 213.36
  4. Step 4: Simplify right side
    429.90x = 137,489.18
  5. Step 5: Solve for x
    x = 137,489.18/429.90
  6. Step 6: Final answer
    x = 319.82

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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.