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Finding the Fourth Proportional to 1,211.87, 1,817.81 and 431.90

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Solution

The fourth proportional to 1,211.87, 1,817.81 and 431.90 is: 647.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,211.87 : 1,817.81 = 431.90 : x
  2. Step 2: Convert to fraction form
    1,211.87/1,817.81 = 431.90/x
  3. Step 3: Cross multiply
    1,211.87x = 1,817.81 × 431.90
  4. Step 4: Simplify right side
    1,211.87x = 785,112.14
  5. Step 5: Solve for x
    x = 785,112.14/1,211.87
  6. Step 6: Final answer
    x = 647.85

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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.