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Finding the Fourth Proportional to 856.80, 1,285.20 and 423.72

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Solution

The fourth proportional to 856.80, 1,285.20 and 423.72 is: 635.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    856.80 : 1,285.20 = 423.72 : x
  2. Step 2: Convert to fraction form
    856.80/1,285.20 = 423.72/x
  3. Step 3: Cross multiply
    856.80x = 1,285.20 × 423.72
  4. Step 4: Simplify right side
    856.80x = 544,564.94
  5. Step 5: Solve for x
    x = 544,564.94/856.80
  6. Step 6: Final answer
    x = 635.58

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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.