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Finding the Fourth Proportional to 865.34, 1,298.21 and 280.38

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Solution

The fourth proportional to 865.34, 1,298.21 and 280.38 is: 420.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    865.34 : 1,298.21 = 280.38 : x
  2. Step 2: Convert to fraction form
    865.34/1,298.21 = 280.38/x
  3. Step 3: Cross multiply
    865.34x = 1,298.21 × 280.38
  4. Step 4: Simplify right side
    865.34x = 363,990.72
  5. Step 5: Solve for x
    x = 363,990.72/865.34
  6. Step 6: Final answer
    x = 420.63

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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.