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Finding the Fourth Proportional to 138.58, 208.86 and 137.21

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Solution

The fourth proportional to 138.58, 208.86 and 137.21 is: 206.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.58 : 208.86 = 137.21 : x
  2. Step 2: Convert to fraction form
    138.58/208.86 = 137.21/x
  3. Step 3: Cross multiply
    138.58x = 208.86 × 137.21
  4. Step 4: Simplify right side
    138.58x = 28,656.12
  5. Step 5: Solve for x
    x = 28,656.12/138.58
  6. Step 6: Final answer
    x = 206.79

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.