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Finding the Fourth Proportional to 428.59, 642.89 and 212.23

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Solution

The fourth proportional to 428.59, 642.89 and 212.23 is: 318.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.59 : 642.89 = 212.23 : x
  2. Step 2: Convert to fraction form
    428.59/642.89 = 212.23/x
  3. Step 3: Cross multiply
    428.59x = 642.89 × 212.23
  4. Step 4: Simplify right side
    428.59x = 136,440.54
  5. Step 5: Solve for x
    x = 136,440.54/428.59
  6. Step 6: Final answer
    x = 318.35

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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.