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Finding the Fourth Proportional to 321.20, 478.38 and 309.86

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Solution

The fourth proportional to 321.20, 478.38 and 309.86 is: 461.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    321.20 : 478.38 = 309.86 : x
  2. Step 2: Convert to fraction form
    321.20/478.38 = 309.86/x
  3. Step 3: Cross multiply
    321.20x = 478.38 × 309.86
  4. Step 4: Simplify right side
    321.20x = 148,230.83
  5. Step 5: Solve for x
    x = 148,230.83/321.20
  6. Step 6: Final answer
    x = 461.49

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.