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Finding the Fourth Proportional to 428.08, 641.56 and 211.72

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Solution

The fourth proportional to 428.08, 641.56 and 211.72 is: 317.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.08 : 641.56 = 211.72 : x
  2. Step 2: Convert to fraction form
    428.08/641.56 = 211.72/x
  3. Step 3: Cross multiply
    428.08x = 641.56 × 211.72
  4. Step 4: Simplify right side
    428.08x = 135,831.08
  5. Step 5: Solve for x
    x = 135,831.08/428.08
  6. Step 6: Final answer
    x = 317.30

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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.