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Finding the Fourth Proportional to 428.20, 642.39 and 154.26

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Solution

The fourth proportional to 428.20, 642.39 and 154.26 is: 231.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.20 : 642.39 = 154.26 : x
  2. Step 2: Convert to fraction form
    428.20/642.39 = 154.26/x
  3. Step 3: Cross multiply
    428.20x = 642.39 × 154.26
  4. Step 4: Simplify right side
    428.20x = 99,095.08
  5. Step 5: Solve for x
    x = 99,095.08/428.20
  6. Step 6: Final answer
    x = 231.42

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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.