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Finding the Fourth Proportional to 820.72, 1,229.80 and 728.36

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Solution

The fourth proportional to 820.72, 1,229.80 and 728.36 is: 1,091.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    820.72 : 1,229.80 = 728.36 : x
  2. Step 2: Convert to fraction form
    820.72/1,229.80 = 728.36/x
  3. Step 3: Cross multiply
    820.72x = 1,229.80 × 728.36
  4. Step 4: Simplify right side
    820.72x = 895,737.13
  5. Step 5: Solve for x
    x = 895,737.13/820.72
  6. Step 6: Final answer
    x = 1,091.40

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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.