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Finding the Fourth Proportional to 81.46, 121.28 and 81.05

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Solution

The fourth proportional to 81.46, 121.28 and 81.05 is: 120.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.46 : 121.28 = 81.05 : x
  2. Step 2: Convert to fraction form
    81.46/121.28 = 81.05/x
  3. Step 3: Cross multiply
    81.46x = 121.28 × 81.05
  4. Step 4: Simplify right side
    81.46x = 9,829.34
  5. Step 5: Solve for x
    x = 9,829.34/81.46
  6. Step 6: Final answer
    x = 120.67

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.