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Finding the Fourth Proportional to 865.42, 1,298.19 and 426.90

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Solution

The fourth proportional to 865.42, 1,298.19 and 426.90 is: 640.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    865.42 : 1,298.19 = 426.90 : x
  2. Step 2: Convert to fraction form
    865.42/1,298.19 = 426.90/x
  3. Step 3: Cross multiply
    865.42x = 1,298.19 × 426.90
  4. Step 4: Simplify right side
    865.42x = 554,195.18
  5. Step 5: Solve for x
    x = 554,195.18/865.42
  6. Step 6: Final answer
    x = 640.38

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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.