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Finding the Fourth Proportional to 686.39, 1,028.29 and 408.16

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Solution

The fourth proportional to 686.39, 1,028.29 and 408.16 is: 611.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.39 : 1,028.29 = 408.16 : x
  2. Step 2: Convert to fraction form
    686.39/1,028.29 = 408.16/x
  3. Step 3: Cross multiply
    686.39x = 1,028.29 × 408.16
  4. Step 4: Simplify right side
    686.39x = 419,706.85
  5. Step 5: Solve for x
    x = 419,706.85/686.39
  6. Step 6: Final answer
    x = 611.47

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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.