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Finding the Fourth Proportional to 853.59, 1,279.17 and 390.21

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Solution

The fourth proportional to 853.59, 1,279.17 and 390.21 is: 584.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    853.59 : 1,279.17 = 390.21 : x
  2. Step 2: Convert to fraction form
    853.59/1,279.17 = 390.21/x
  3. Step 3: Cross multiply
    853.59x = 1,279.17 × 390.21
  4. Step 4: Simplify right side
    853.59x = 499,144.93
  5. Step 5: Solve for x
    x = 499,144.93/853.59
  6. Step 6: Final answer
    x = 584.76

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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.