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Finding the Fourth Proportional to 865.90, 1,298.65 and 426.72

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Solution

The fourth proportional to 865.90, 1,298.65 and 426.72 is: 639.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    865.90 : 1,298.65 = 426.72 : x
  2. Step 2: Convert to fraction form
    865.90/1,298.65 = 426.72/x
  3. Step 3: Cross multiply
    865.90x = 1,298.65 × 426.72
  4. Step 4: Simplify right side
    865.90x = 554,159.93
  5. Step 5: Solve for x
    x = 554,159.93/865.90
  6. Step 6: Final answer
    x = 639.98

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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.