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Finding the Fourth Proportional to 865.76, 1,298.76 and 318.71

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Solution

The fourth proportional to 865.76, 1,298.76 and 318.71 is: 478.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    865.76 : 1,298.76 = 318.71 : x
  2. Step 2: Convert to fraction form
    865.76/1,298.76 = 318.71/x
  3. Step 3: Cross multiply
    865.76x = 1,298.76 × 318.71
  4. Step 4: Simplify right side
    865.76x = 413,921.31
  5. Step 5: Solve for x
    x = 413,921.31/865.76
  6. Step 6: Final answer
    x = 478.10

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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.