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Finding the Fourth Proportional to 1,138.92, 1,706.90 and 489

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Solution

The fourth proportional to 1,138.92, 1,706.90 and 489 is: 732.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,138.92 : 1,706.90 = 489 : x
  2. Step 2: Convert to fraction form
    1,138.92/1,706.90 = 489/x
  3. Step 3: Cross multiply
    1,138.92x = 1,706.90 × 489
  4. Step 4: Simplify right side
    1,138.92x = 834,674.10
  5. Step 5: Solve for x
    x = 834,674.10/1,138.92
  6. Step 6: Final answer
    x = 732.86

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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.