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Finding the Fourth Proportional to 428.47, 642.70 and 103.83

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Solution

The fourth proportional to 428.47, 642.70 and 103.83 is: 155.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.47 : 642.70 = 103.83 : x
  2. Step 2: Convert to fraction form
    428.47/642.70 = 103.83/x
  3. Step 3: Cross multiply
    428.47x = 642.70 × 103.83
  4. Step 4: Simplify right side
    428.47x = 66,732.89
  5. Step 5: Solve for x
    x = 66,732.89/428.47
  6. Step 6: Final answer
    x = 155.75

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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.