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Finding the Fourth Proportional to 781.58, 1,078.54 and 486.85

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Solution

The fourth proportional to 781.58, 1,078.54 and 486.85 is: 671.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.58 : 1,078.54 = 486.85 : x
  2. Step 2: Convert to fraction form
    781.58/1,078.54 = 486.85/x
  3. Step 3: Cross multiply
    781.58x = 1,078.54 × 486.85
  4. Step 4: Simplify right side
    781.58x = 525,087.20
  5. Step 5: Solve for x
    x = 525,087.20/781.58
  6. Step 6: Final answer
    x = 671.83

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.