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Finding the Fourth Proportional to 820.20, 1,230.30 and 775.40

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Solution

The fourth proportional to 820.20, 1,230.30 and 775.40 is: 1,163.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    820.20 : 1,230.30 = 775.40 : x
  2. Step 2: Convert to fraction form
    820.20/1,230.30 = 775.40/x
  3. Step 3: Cross multiply
    820.20x = 1,230.30 × 775.40
  4. Step 4: Simplify right side
    820.20x = 953,974.62
  5. Step 5: Solve for x
    x = 953,974.62/820.20
  6. Step 6: Final answer
    x = 1,163.10

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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.