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Finding the Fourth Proportional to 429.60, 643.98 and 391.56

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Solution

The fourth proportional to 429.60, 643.98 and 391.56 is: 586.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    429.60 : 643.98 = 391.56 : x
  2. Step 2: Convert to fraction form
    429.60/643.98 = 391.56/x
  3. Step 3: Cross multiply
    429.60x = 643.98 × 391.56
  4. Step 4: Simplify right side
    429.60x = 252,156.81
  5. Step 5: Solve for x
    x = 252,156.81/429.60
  6. Step 6: Final answer
    x = 586.96

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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.