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Finding the Fourth Proportional to 91.20, 136.09 and 81.46

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Solution

The fourth proportional to 91.20, 136.09 and 81.46 is: 121.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.20 : 136.09 = 81.46 : x
  2. Step 2: Convert to fraction form
    91.20/136.09 = 81.46/x
  3. Step 3: Cross multiply
    91.20x = 136.09 × 81.46
  4. Step 4: Simplify right side
    91.20x = 11,085.89
  5. Step 5: Solve for x
    x = 11,085.89/91.20
  6. Step 6: Final answer
    x = 121.56

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.