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Finding the Fourth Proportional to 428.43, 642.24 and 211.77

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Solution

The fourth proportional to 428.43, 642.24 and 211.77 is: 317.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.43 : 642.24 = 211.77 : x
  2. Step 2: Convert to fraction form
    428.43/642.24 = 211.77/x
  3. Step 3: Cross multiply
    428.43x = 642.24 × 211.77
  4. Step 4: Simplify right side
    428.43x = 136,007.16
  5. Step 5: Solve for x
    x = 136,007.16/428.43
  6. Step 6: Final answer
    x = 317.45

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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.