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Finding the Fourth Proportional to 121.32, 181.89 and 90.81

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Solution

The fourth proportional to 121.32, 181.89 and 90.81 is: 136.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.32 : 181.89 = 90.81 : x
  2. Step 2: Convert to fraction form
    121.32/181.89 = 90.81/x
  3. Step 3: Cross multiply
    121.32x = 181.89 × 90.81
  4. Step 4: Simplify right side
    121.32x = 16,517.43
  5. Step 5: Solve for x
    x = 16,517.43/121.32
  6. Step 6: Final answer
    x = 136.15

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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.