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Finding the Fourth Proportional to 857.20, 1,285.78 and 280.07

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Solution

The fourth proportional to 857.20, 1,285.78 and 280.07 is: 420.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    857.20 : 1,285.78 = 280.07 : x
  2. Step 2: Convert to fraction form
    857.20/1,285.78 = 280.07/x
  3. Step 3: Cross multiply
    857.20x = 1,285.78 × 280.07
  4. Step 4: Simplify right side
    857.20x = 360,108.40
  5. Step 5: Solve for x
    x = 360,108.40/857.20
  6. Step 6: Final answer
    x = 420.10

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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.