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Finding the Fourth Proportional to 259.78, 389.40 and 137.78

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Solution

The fourth proportional to 259.78, 389.40 and 137.78 is: 206.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    259.78 : 389.40 = 137.78 : x
  2. Step 2: Convert to fraction form
    259.78/389.40 = 137.78/x
  3. Step 3: Cross multiply
    259.78x = 389.40 × 137.78
  4. Step 4: Simplify right side
    259.78x = 53,651.53
  5. Step 5: Solve for x
    x = 53,651.53/259.78
  6. Step 6: Final answer
    x = 206.53

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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.