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Finding the Fourth Proportional to 686.21, 1,028.79 and 320.99

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Solution

The fourth proportional to 686.21, 1,028.79 and 320.99 is: 481.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.21 : 1,028.79 = 320.99 : x
  2. Step 2: Convert to fraction form
    686.21/1,028.79 = 320.99/x
  3. Step 3: Cross multiply
    686.21x = 1,028.79 × 320.99
  4. Step 4: Simplify right side
    686.21x = 330,226.16
  5. Step 5: Solve for x
    x = 330,226.16/686.21
  6. Step 6: Final answer
    x = 481.24

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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.