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Finding the Fourth Proportional to 1,238.50, 1,856.18 and 689.90

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Solution

The fourth proportional to 1,238.50, 1,856.18 and 689.90 is: 1,033.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,238.50 : 1,856.18 = 689.90 : x
  2. Step 2: Convert to fraction form
    1,238.50/1,856.18 = 689.90/x
  3. Step 3: Cross multiply
    1,238.50x = 1,856.18 × 689.90
  4. Step 4: Simplify right side
    1,238.50x = 1,280,578.58
  5. Step 5: Solve for x
    x = 1,280,578.58/1,238.50
  6. Step 6: Final answer
    x = 1,033.98

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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.