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Finding the Fourth Proportional to 853.90, 1,280.21 and 442.80

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Solution

The fourth proportional to 853.90, 1,280.21 and 442.80 is: 663.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    853.90 : 1,280.21 = 442.80 : x
  2. Step 2: Convert to fraction form
    853.90/1,280.21 = 442.80/x
  3. Step 3: Cross multiply
    853.90x = 1,280.21 × 442.80
  4. Step 4: Simplify right side
    853.90x = 566,874.77
  5. Step 5: Solve for x
    x = 566,874.77/853.90
  6. Step 6: Final answer
    x = 663.87

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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.