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Finding the Fourth Proportional to 939.20, 1,408.80 and 611.15

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Solution

The fourth proportional to 939.20, 1,408.80 and 611.15 is: 916.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    939.20 : 1,408.80 = 611.15 : x
  2. Step 2: Convert to fraction form
    939.20/1,408.80 = 611.15/x
  3. Step 3: Cross multiply
    939.20x = 1,408.80 × 611.15
  4. Step 4: Simplify right side
    939.20x = 860,988.12
  5. Step 5: Solve for x
    x = 860,988.12/939.20
  6. Step 6: Final answer
    x = 916.73

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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.