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Finding the Fourth Proportional to 857.60, 1,285.92 and 280.40

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Solution

The fourth proportional to 857.60, 1,285.92 and 280.40 is: 420.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    857.60 : 1,285.92 = 280.40 : x
  2. Step 2: Convert to fraction form
    857.60/1,285.92 = 280.40/x
  3. Step 3: Cross multiply
    857.60x = 1,285.92 × 280.40
  4. Step 4: Simplify right side
    857.60x = 360,571.97
  5. Step 5: Solve for x
    x = 360,571.97/857.60
  6. Step 6: Final answer
    x = 420.44

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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.