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Finding the Fourth Proportional to 428.42, 642.38 and 135.84

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Solution

The fourth proportional to 428.42, 642.38 and 135.84 is: 203.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.42 : 642.38 = 135.84 : x
  2. Step 2: Convert to fraction form
    428.42/642.38 = 135.84/x
  3. Step 3: Cross multiply
    428.42x = 642.38 × 135.84
  4. Step 4: Simplify right side
    428.42x = 87,260.22
  5. Step 5: Solve for x
    x = 87,260.22/428.42
  6. Step 6: Final answer
    x = 203.68

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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.