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Finding the Fourth Proportional to 259.65, 390.20 and 138

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Solution

The fourth proportional to 259.65, 390.20 and 138 is: 207.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    259.65 : 390.20 = 138 : x
  2. Step 2: Convert to fraction form
    259.65/390.20 = 138/x
  3. Step 3: Cross multiply
    259.65x = 390.20 × 138
  4. Step 4: Simplify right side
    259.65x = 53,846.91
  5. Step 5: Solve for x
    x = 53,846.91/259.65
  6. Step 6: Final answer
    x = 207.38

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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.