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Finding the Fourth Proportional to 259.82, 389.78 and 77.20

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Solution

The fourth proportional to 259.82, 389.78 and 77.20 is: 115.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    259.82 : 389.78 = 77.20 : x
  2. Step 2: Convert to fraction form
    259.82/389.78 = 77.20/x
  3. Step 3: Cross multiply
    259.82x = 389.78 × 77.20
  4. Step 4: Simplify right side
    259.82x = 30,091.02
  5. Step 5: Solve for x
    x = 30,091.02/259.82
  6. Step 6: Final answer
    x = 115.81

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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.