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Finding the Fourth Proportional to 428.38, 642.56 and 172.06

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Solution

The fourth proportional to 428.38, 642.56 and 172.06 is: 258.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.38 : 642.56 = 172.06 : x
  2. Step 2: Convert to fraction form
    428.38/642.56 = 172.06/x
  3. Step 3: Cross multiply
    428.38x = 642.56 × 172.06
  4. Step 4: Simplify right side
    428.38x = 110,558.87
  5. Step 5: Solve for x
    x = 110,558.87/428.38
  6. Step 6: Final answer
    x = 258.09

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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.