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Finding the Fourth Proportional to 259.80, 389.72 and 77.18

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Solution

The fourth proportional to 259.80, 389.72 and 77.18 is: 115.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    259.80 : 389.72 = 77.18 : x
  2. Step 2: Convert to fraction form
    259.80/389.72 = 77.18/x
  3. Step 3: Cross multiply
    259.80x = 389.72 × 77.18
  4. Step 4: Simplify right side
    259.80x = 30,078.59
  5. Step 5: Solve for x
    x = 30,078.59/259.80
  6. Step 6: Final answer
    x = 115.78

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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.