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Finding the Fourth Proportional to 422.70, 642.18 and 422.70

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Solution

The fourth proportional to 422.70, 642.18 and 422.70 is: 642.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    422.70 : 642.18 = 422.70 : x
  2. Step 2: Convert to fraction form
    422.70/642.18 = 422.70/x
  3. Step 3: Cross multiply
    422.70x = 642.18 × 422.70
  4. Step 4: Simplify right side
    422.70x = 271,449.49
  5. Step 5: Solve for x
    x = 271,449.49/422.70
  6. Step 6: Final answer
    x = 642.18

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Why These Related Problems?

These problems maintain the same ratio (1.52) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.