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Finding the Fourth Proportional to 121.81, 182.69 and 81.21

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Solution

The fourth proportional to 121.81, 182.69 and 81.21 is: 121.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.81 : 182.69 = 81.21 : x
  2. Step 2: Convert to fraction form
    121.81/182.69 = 81.21/x
  3. Step 3: Cross multiply
    121.81x = 182.69 × 81.21
  4. Step 4: Simplify right side
    121.81x = 14,835.14
  5. Step 5: Solve for x
    x = 14,835.14/121.81
  6. Step 6: Final answer
    x = 121.79

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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.