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Finding the Fourth Proportional to 920.11, 1,380.39 and 426.87

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Solution

The fourth proportional to 920.11, 1,380.39 and 426.87 is: 640.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    920.11 : 1,380.39 = 426.87 : x
  2. Step 2: Convert to fraction form
    920.11/1,380.39 = 426.87/x
  3. Step 3: Cross multiply
    920.11x = 1,380.39 × 426.87
  4. Step 4: Simplify right side
    920.11x = 589,247.08
  5. Step 5: Solve for x
    x = 589,247.08/920.11
  6. Step 6: Final answer
    x = 640.41

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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.