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Finding the Fourth Proportional to 1,139.87, 1,709.17 and 728.75

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Solution

The fourth proportional to 1,139.87, 1,709.17 and 728.75 is: 1,092.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,139.87 : 1,709.17 = 728.75 : x
  2. Step 2: Convert to fraction form
    1,139.87/1,709.17 = 728.75/x
  3. Step 3: Cross multiply
    1,139.87x = 1,709.17 × 728.75
  4. Step 4: Simplify right side
    1,139.87x = 1,245,557.64
  5. Step 5: Solve for x
    x = 1,245,557.64/1,139.87
  6. Step 6: Final answer
    x = 1,092.72

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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.