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Finding the Fourth Proportional to 429.12, 639.72 and 394.56

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Solution

The fourth proportional to 429.12, 639.72 and 394.56 is: 588.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    429.12 : 639.72 = 394.56 : x
  2. Step 2: Convert to fraction form
    429.12/639.72 = 394.56/x
  3. Step 3: Cross multiply
    429.12x = 639.72 × 394.56
  4. Step 4: Simplify right side
    429.12x = 252,407.92
  5. Step 5: Solve for x
    x = 252,407.92/429.12
  6. Step 6: Final answer
    x = 588.20

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.