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Finding the Fourth Proportional to 938.80, 1,408.20 and 871.30

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Solution

The fourth proportional to 938.80, 1,408.20 and 871.30 is: 1,306.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    938.80 : 1,408.20 = 871.30 : x
  2. Step 2: Convert to fraction form
    938.80/1,408.20 = 871.30/x
  3. Step 3: Cross multiply
    938.80x = 1,408.20 × 871.30
  4. Step 4: Simplify right side
    938.80x = 1,226,964.66
  5. Step 5: Solve for x
    x = 1,226,964.66/938.80
  6. Step 6: Final answer
    x = 1,306.95

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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.