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Finding the Fourth Proportional to 139.42, 208.69 and 121.20

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Solution

The fourth proportional to 139.42, 208.69 and 121.20 is: 181.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.42 : 208.69 = 121.20 : x
  2. Step 2: Convert to fraction form
    139.42/208.69 = 121.20/x
  3. Step 3: Cross multiply
    139.42x = 208.69 × 121.20
  4. Step 4: Simplify right side
    139.42x = 25,293.23
  5. Step 5: Solve for x
    x = 25,293.23/139.42
  6. Step 6: Final answer
    x = 181.42

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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.