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Finding the Fourth Proportional to 121.38, 181.81 and 90.57

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Solution

The fourth proportional to 121.38, 181.81 and 90.57 is: 135.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.38 : 181.81 = 90.57 : x
  2. Step 2: Convert to fraction form
    121.38/181.81 = 90.57/x
  3. Step 3: Cross multiply
    121.38x = 181.81 × 90.57
  4. Step 4: Simplify right side
    121.38x = 16,466.82
  5. Step 5: Solve for x
    x = 16,466.82/121.38
  6. Step 6: Final answer
    x = 135.67

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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.