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Finding the Fourth Proportional to 139.12, 191.98 and 80.90

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Solution

The fourth proportional to 139.12, 191.98 and 80.90 is: 111.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.12 : 191.98 = 80.90 : x
  2. Step 2: Convert to fraction form
    139.12/191.98 = 80.90/x
  3. Step 3: Cross multiply
    139.12x = 191.98 × 80.90
  4. Step 4: Simplify right side
    139.12x = 15,531.18
  5. Step 5: Solve for x
    x = 15,531.18/139.12
  6. Step 6: Final answer
    x = 111.64

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.