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Finding the Fourth Proportional to 1,311.05, 1,966.39 and 489.21

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Solution

The fourth proportional to 1,311.05, 1,966.39 and 489.21 is: 733.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,311.05 : 1,966.39 = 489.21 : x
  2. Step 2: Convert to fraction form
    1,311.05/1,966.39 = 489.21/x
  3. Step 3: Cross multiply
    1,311.05x = 1,966.39 × 489.21
  4. Step 4: Simplify right side
    1,311.05x = 961,977.65
  5. Step 5: Solve for x
    x = 961,977.65/1,311.05
  6. Step 6: Final answer
    x = 733.75

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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.