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Finding the Fourth Proportional to 429.18, 643.44 and 212.59

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Solution

The fourth proportional to 429.18, 643.44 and 212.59 is: 318.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    429.18 : 643.44 = 212.59 : x
  2. Step 2: Convert to fraction form
    429.18/643.44 = 212.59/x
  3. Step 3: Cross multiply
    429.18x = 643.44 × 212.59
  4. Step 4: Simplify right side
    429.18x = 136,788.91
  5. Step 5: Solve for x
    x = 136,788.91/429.18
  6. Step 6: Final answer
    x = 318.72

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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.