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Finding the Fourth Proportional to 90.72, 136.05 and 81.14

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Solution

The fourth proportional to 90.72, 136.05 and 81.14 is: 121.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.72 : 136.05 = 81.14 : x
  2. Step 2: Convert to fraction form
    90.72/136.05 = 81.14/x
  3. Step 3: Cross multiply
    90.72x = 136.05 × 81.14
  4. Step 4: Simplify right side
    90.72x = 11,038.11
  5. Step 5: Solve for x
    x = 11,038.11/90.72
  6. Step 6: Final answer
    x = 121.67

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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.