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Finding the Fourth Proportional to 429.76, 643.98 and 213.46

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Solution

The fourth proportional to 429.76, 643.98 and 213.46 is: 319.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    429.76 : 643.98 = 213.46 : x
  2. Step 2: Convert to fraction form
    429.76/643.98 = 213.46/x
  3. Step 3: Cross multiply
    429.76x = 643.98 × 213.46
  4. Step 4: Simplify right side
    429.76x = 137,463.97
  5. Step 5: Solve for x
    x = 137,463.97/429.76
  6. Step 6: Final answer
    x = 319.86

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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.