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Finding the Fourth Proportional to 318.72, 478.85 and 261.31

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Solution

The fourth proportional to 318.72, 478.85 and 261.31 is: 392.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    318.72 : 478.85 = 261.31 : x
  2. Step 2: Convert to fraction form
    318.72/478.85 = 261.31/x
  3. Step 3: Cross multiply
    318.72x = 478.85 × 261.31
  4. Step 4: Simplify right side
    318.72x = 125,128.29
  5. Step 5: Solve for x
    x = 125,128.29/318.72
  6. Step 6: Final answer
    x = 392.60

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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.