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Finding the Fourth Proportional to 126.96, 190.32 and 81.21

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Solution

The fourth proportional to 126.96, 190.32 and 81.21 is: 121.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    126.96 : 190.32 = 81.21 : x
  2. Step 2: Convert to fraction form
    126.96/190.32 = 81.21/x
  3. Step 3: Cross multiply
    126.96x = 190.32 × 81.21
  4. Step 4: Simplify right side
    126.96x = 15,455.89
  5. Step 5: Solve for x
    x = 15,455.89/126.96
  6. Step 6: Final answer
    x = 121.74

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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.