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Finding the Fourth Proportional to 618.20, 853.28 and 421.64

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Solution

The fourth proportional to 618.20, 853.28 and 421.64 is: 581.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    618.20 : 853.28 = 421.64 : x
  2. Step 2: Convert to fraction form
    618.20/853.28 = 421.64/x
  3. Step 3: Cross multiply
    618.20x = 853.28 × 421.64
  4. Step 4: Simplify right side
    618.20x = 359,776.98
  5. Step 5: Solve for x
    x = 359,776.98/618.20
  6. Step 6: Final answer
    x = 581.98

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.