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Finding the Fourth Proportional to 856.70, 1,285.05 and 423.80

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Solution

The fourth proportional to 856.70, 1,285.05 and 423.80 is: 635.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    856.70 : 1,285.05 = 423.80 : x
  2. Step 2: Convert to fraction form
    856.70/1,285.05 = 423.80/x
  3. Step 3: Cross multiply
    856.70x = 1,285.05 × 423.80
  4. Step 4: Simplify right side
    856.70x = 544,604.19
  5. Step 5: Solve for x
    x = 544,604.19/856.70
  6. Step 6: Final answer
    x = 635.70

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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.