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Finding the Fourth Proportional to 428.31, 642.22 and 135.67

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Solution

The fourth proportional to 428.31, 642.22 and 135.67 is: 203.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.31 : 642.22 = 135.67 : x
  2. Step 2: Convert to fraction form
    428.31/642.22 = 135.67/x
  3. Step 3: Cross multiply
    428.31x = 642.22 × 135.67
  4. Step 4: Simplify right side
    428.31x = 87,129.99
  5. Step 5: Solve for x
    x = 87,129.99/428.31
  6. Step 6: Final answer
    x = 203.43

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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.