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Finding the Fourth Proportional to 928, 1,391.46 and 820

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Solution

The fourth proportional to 928, 1,391.46 and 820 is: 1,229.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    928 : 1,391.46 = 820 : x
  2. Step 2: Convert to fraction form
    928/1,391.46 = 820/x
  3. Step 3: Cross multiply
    928x = 1,391.46 × 820
  4. Step 4: Simplify right side
    928x = 1,140,997.20
  5. Step 5: Solve for x
    x = 1,140,997.20/928
  6. Step 6: Final answer
    x = 1,229.52

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These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.