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Finding the Fourth Proportional to 781.72, 1,078.04 and 486.78

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Solution

The fourth proportional to 781.72, 1,078.04 and 486.78 is: 671.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.72 : 1,078.04 = 486.78 : x
  2. Step 2: Convert to fraction form
    781.72/1,078.04 = 486.78/x
  3. Step 3: Cross multiply
    781.72x = 1,078.04 × 486.78
  4. Step 4: Simplify right side
    781.72x = 524,768.31
  5. Step 5: Solve for x
    x = 524,768.31/781.72
  6. Step 6: Final answer
    x = 671.30

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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.