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Finding the Fourth Proportional to 91.15, 136.14 and 81.49

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Solution

The fourth proportional to 91.15, 136.14 and 81.49 is: 121.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.15 : 136.14 = 81.49 : x
  2. Step 2: Convert to fraction form
    91.15/136.14 = 81.49/x
  3. Step 3: Cross multiply
    91.15x = 136.14 × 81.49
  4. Step 4: Simplify right side
    91.15x = 11,094.05
  5. Step 5: Solve for x
    x = 11,094.05/91.15
  6. Step 6: Final answer
    x = 121.71

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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.