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Finding the Fourth Proportional to 138.48, 207.78 and 66.39

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Solution

The fourth proportional to 138.48, 207.78 and 66.39 is: 99.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.48 : 207.78 = 66.39 : x
  2. Step 2: Convert to fraction form
    138.48/207.78 = 66.39/x
  3. Step 3: Cross multiply
    138.48x = 207.78 × 66.39
  4. Step 4: Simplify right side
    138.48x = 13,794.51
  5. Step 5: Solve for x
    x = 13,794.51/138.48
  6. Step 6: Final answer
    x = 99.61

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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.