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Finding the Fourth Proportional to 428.15, 642.24 and 135.65

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Solution

The fourth proportional to 428.15, 642.24 and 135.65 is: 203.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.15 : 642.24 = 135.65 : x
  2. Step 2: Convert to fraction form
    428.15/642.24 = 135.65/x
  3. Step 3: Cross multiply
    428.15x = 642.24 × 135.65
  4. Step 4: Simplify right side
    428.15x = 87,121.46
  5. Step 5: Solve for x
    x = 87,121.46/428.15
  6. Step 6: Final answer
    x = 203.48

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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.