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Finding the Fourth Proportional to 856.87, 1,285.48 and 280.15

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Solution

The fourth proportional to 856.87, 1,285.48 and 280.15 is: 420.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    856.87 : 1,285.48 = 280.15 : x
  2. Step 2: Convert to fraction form
    856.87/1,285.48 = 280.15/x
  3. Step 3: Cross multiply
    856.87x = 1,285.48 × 280.15
  4. Step 4: Simplify right side
    856.87x = 360,127.22
  5. Step 5: Solve for x
    x = 360,127.22/856.87
  6. Step 6: Final answer
    x = 420.28

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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.