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Finding the Fourth Proportional to 865.75, 1,305.90 and 815.23

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Solution

The fourth proportional to 865.75, 1,305.90 and 815.23 is: 1,229.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    865.75 : 1,305.90 = 815.23 : x
  2. Step 2: Convert to fraction form
    865.75/1,305.90 = 815.23/x
  3. Step 3: Cross multiply
    865.75x = 1,305.90 × 815.23
  4. Step 4: Simplify right side
    865.75x = 1,064,604.78
  5. Step 5: Solve for x
    x = 1,064,604.78/865.75
  6. Step 6: Final answer
    x = 1,229.69

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.