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Finding the Fourth Proportional to 865.76, 1,297.76 and 426.80

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Solution

The fourth proportional to 865.76, 1,297.76 and 426.80 is: 639.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    865.76 : 1,297.76 = 426.80 : x
  2. Step 2: Convert to fraction form
    865.76/1,297.76 = 426.80/x
  3. Step 3: Cross multiply
    865.76x = 1,297.76 × 426.80
  4. Step 4: Simplify right side
    865.76x = 553,883.97
  5. Step 5: Solve for x
    x = 553,883.97/865.76
  6. Step 6: Final answer
    x = 639.77

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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.