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Finding the Fourth Proportional to 856.62, 1,285.20 and 640.62

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Solution

The fourth proportional to 856.62, 1,285.20 and 640.62 is: 961.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    856.62 : 1,285.20 = 640.62 : x
  2. Step 2: Convert to fraction form
    856.62/1,285.20 = 640.62/x
  3. Step 3: Cross multiply
    856.62x = 1,285.20 × 640.62
  4. Step 4: Simplify right side
    856.62x = 823,324.82
  5. Step 5: Solve for x
    x = 823,324.82/856.62
  6. Step 6: Final answer
    x = 961.13

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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.