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Finding the Fourth Proportional to 865.75, 1,298.85 and 280.75

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Solution

The fourth proportional to 865.75, 1,298.85 and 280.75 is: 421.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    865.75 : 1,298.85 = 280.75 : x
  2. Step 2: Convert to fraction form
    865.75/1,298.85 = 280.75/x
  3. Step 3: Cross multiply
    865.75x = 1,298.85 × 280.75
  4. Step 4: Simplify right side
    865.75x = 364,652.14
  5. Step 5: Solve for x
    x = 364,652.14/865.75
  6. Step 6: Final answer
    x = 421.20

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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.