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Finding the Fourth Proportional to 81.81, 122 and 81.08

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Solution

The fourth proportional to 81.81, 122 and 81.08 is: 120.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.81 : 122 = 81.08 : x
  2. Step 2: Convert to fraction form
    81.81/122 = 81.08/x
  3. Step 3: Cross multiply
    81.81x = 122 × 81.08
  4. Step 4: Simplify right side
    81.81x = 9,891.76
  5. Step 5: Solve for x
    x = 9,891.76/81.81
  6. Step 6: Final answer
    x = 120.91

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1.5x scale

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.