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Finding the Fourth Proportional to 678.93, 1,016.78 and 389.49

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Solution

The fourth proportional to 678.93, 1,016.78 and 389.49 is: 583.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.93 : 1,016.78 = 389.49 : x
  2. Step 2: Convert to fraction form
    678.93/1,016.78 = 389.49/x
  3. Step 3: Cross multiply
    678.93x = 1,016.78 × 389.49
  4. Step 4: Simplify right side
    678.93x = 396,023.69
  5. Step 5: Solve for x
    x = 396,023.69/678.93
  6. Step 6: Final answer
    x = 583.31

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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.