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Finding the Fourth Proportional to 428.49, 642.44 and 135.89

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Solution

The fourth proportional to 428.49, 642.44 and 135.89 is: 203.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.49 : 642.44 = 135.89 : x
  2. Step 2: Convert to fraction form
    428.49/642.44 = 135.89/x
  3. Step 3: Cross multiply
    428.49x = 642.44 × 135.89
  4. Step 4: Simplify right side
    428.49x = 87,303.56
  5. Step 5: Solve for x
    x = 87,303.56/428.49
  6. Step 6: Final answer
    x = 203.75

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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.