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Finding the Fourth Proportional to 781.26, 1,078.20 and 486.60

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Solution

The fourth proportional to 781.26, 1,078.20 and 486.60 is: 671.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.26 : 1,078.20 = 486.60 : x
  2. Step 2: Convert to fraction form
    781.26/1,078.20 = 486.60/x
  3. Step 3: Cross multiply
    781.26x = 1,078.20 × 486.60
  4. Step 4: Simplify right side
    781.26x = 524,652.12
  5. Step 5: Solve for x
    x = 524,652.12/781.26
  6. Step 6: Final answer
    x = 671.55

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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.