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Finding the Fourth Proportional to 686.64, 1,028.34 and 640.47

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Solution

The fourth proportional to 686.64, 1,028.34 and 640.47 is: 959.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.64 : 1,028.34 = 640.47 : x
  2. Step 2: Convert to fraction form
    686.64/1,028.34 = 640.47/x
  3. Step 3: Cross multiply
    686.64x = 1,028.34 × 640.47
  4. Step 4: Simplify right side
    686.64x = 658,620.92
  5. Step 5: Solve for x
    x = 658,620.92/686.64
  6. Step 6: Final answer
    x = 959.19

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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.