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Finding the Fourth Proportional to 687.17, 1,029.85 and 321.15

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Solution

The fourth proportional to 687.17, 1,029.85 and 321.15 is: 481.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.17 : 1,029.85 = 321.15 : x
  2. Step 2: Convert to fraction form
    687.17/1,029.85 = 321.15/x
  3. Step 3: Cross multiply
    687.17x = 1,029.85 × 321.15
  4. Step 4: Simplify right side
    687.17x = 330,739.39
  5. Step 5: Solve for x
    x = 330,739.39/687.17
  6. Step 6: Final answer
    x = 481.30

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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.