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Finding the Fourth Proportional to 90.68, 136.17 and 80.42

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Solution

The fourth proportional to 90.68, 136.17 and 80.42 is: 120.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.68 : 136.17 = 80.42 : x
  2. Step 2: Convert to fraction form
    90.68/136.17 = 80.42/x
  3. Step 3: Cross multiply
    90.68x = 136.17 × 80.42
  4. Step 4: Simplify right side
    90.68x = 10,950.11
  5. Step 5: Solve for x
    x = 10,950.11/90.68
  6. Step 6: Final answer
    x = 120.76

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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.