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Finding the Fourth Proportional to 1,238.62, 1,856.70 and 689.66

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Solution

The fourth proportional to 1,238.62, 1,856.70 and 689.66 is: 1,033.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,238.62 : 1,856.70 = 689.66 : x
  2. Step 2: Convert to fraction form
    1,238.62/1,856.70 = 689.66/x
  3. Step 3: Cross multiply
    1,238.62x = 1,856.70 × 689.66
  4. Step 4: Simplify right side
    1,238.62x = 1,280,491.72
  5. Step 5: Solve for x
    x = 1,280,491.72/1,238.62
  6. Step 6: Final answer
    x = 1,033.81

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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.