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Finding the Fourth Proportional to 91.18, 136.79 and 81.11

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Solution

The fourth proportional to 91.18, 136.79 and 81.11 is: 121.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.18 : 136.79 = 81.11 : x
  2. Step 2: Convert to fraction form
    91.18/136.79 = 81.11/x
  3. Step 3: Cross multiply
    91.18x = 136.79 × 81.11
  4. Step 4: Simplify right side
    91.18x = 11,095.04
  5. Step 5: Solve for x
    x = 11,095.04/91.18
  6. Step 6: Final answer
    x = 121.68

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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.