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Finding the Fourth Proportional to 81.13, 121.85 and 55.51

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Solution

The fourth proportional to 81.13, 121.85 and 55.51 is: 83.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.13 : 121.85 = 55.51 : x
  2. Step 2: Convert to fraction form
    81.13/121.85 = 55.51/x
  3. Step 3: Cross multiply
    81.13x = 121.85 × 55.51
  4. Step 4: Simplify right side
    81.13x = 6,764.17
  5. Step 5: Solve for x
    x = 6,764.17/81.13
  6. Step 6: Final answer
    x = 83.38

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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.