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Finding the Fourth Proportional to 823.80, 1,234.71 and 390.72

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Solution

The fourth proportional to 823.80, 1,234.71 and 390.72 is: 585.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    823.80 : 1,234.71 = 390.72 : x
  2. Step 2: Convert to fraction form
    823.80/1,234.71 = 390.72/x
  3. Step 3: Cross multiply
    823.80x = 1,234.71 × 390.72
  4. Step 4: Simplify right side
    823.80x = 482,425.89
  5. Step 5: Solve for x
    x = 482,425.89/823.80
  6. Step 6: Final answer
    x = 585.61

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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.