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Finding the Fourth Proportional to 820.74, 1,231.62 and 455.78

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Solution

The fourth proportional to 820.74, 1,231.62 and 455.78 is: 683.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    820.74 : 1,231.62 = 455.78 : x
  2. Step 2: Convert to fraction form
    820.74/1,231.62 = 455.78/x
  3. Step 3: Cross multiply
    820.74x = 1,231.62 × 455.78
  4. Step 4: Simplify right side
    820.74x = 561,341.61
  5. Step 5: Solve for x
    x = 561,341.61/820.74
  6. Step 6: Final answer
    x = 683.95

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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.