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Finding the Fourth Proportional to 1,028.90, 1,542.85 and 639.39

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Solution

The fourth proportional to 1,028.90, 1,542.85 and 639.39 is: 958.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,028.90 : 1,542.85 = 639.39 : x
  2. Step 2: Convert to fraction form
    1,028.90/1,542.85 = 639.39/x
  3. Step 3: Cross multiply
    1,028.90x = 1,542.85 × 639.39
  4. Step 4: Simplify right side
    1,028.90x = 986,487.05
  5. Step 5: Solve for x
    x = 986,487.05/1,028.90
  6. Step 6: Final answer
    x = 958.78

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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.