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Finding the Fourth Proportional to 91.31, 136.85 and 79.88

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Solution

The fourth proportional to 91.31, 136.85 and 79.88 is: 119.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.31 : 136.85 = 79.88 : x
  2. Step 2: Convert to fraction form
    91.31/136.85 = 79.88/x
  3. Step 3: Cross multiply
    91.31x = 136.85 × 79.88
  4. Step 4: Simplify right side
    91.31x = 10,930.49
  5. Step 5: Solve for x
    x = 10,930.49/91.31
  6. Step 6: Final answer
    x = 119.71

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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.