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Finding the Fourth Proportional to 259.39, 389.12 and 76.78

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Solution

The fourth proportional to 259.39, 389.12 and 76.78 is: 115.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    259.39 : 389.12 = 76.78 : x
  2. Step 2: Convert to fraction form
    259.39/389.12 = 76.78/x
  3. Step 3: Cross multiply
    259.39x = 389.12 × 76.78
  4. Step 4: Simplify right side
    259.39x = 29,876.63
  5. Step 5: Solve for x
    x = 29,876.63/259.39
  6. Step 6: Final answer
    x = 115.18

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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.