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Finding the Fourth Proportional to 820.50, 1,229.21 and 409.15

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Solution

The fourth proportional to 820.50, 1,229.21 and 409.15 is: 612.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    820.50 : 1,229.21 = 409.15 : x
  2. Step 2: Convert to fraction form
    820.50/1,229.21 = 409.15/x
  3. Step 3: Cross multiply
    820.50x = 1,229.21 × 409.15
  4. Step 4: Simplify right side
    820.50x = 502,932.30
  5. Step 5: Solve for x
    x = 502,932.30/820.50
  6. Step 6: Final answer
    x = 612.96

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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.