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Finding the Fourth Proportional to 81.88, 121.98 and 79.76

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Solution

The fourth proportional to 81.88, 121.98 and 79.76 is: 118.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.88 : 121.98 = 79.76 : x
  2. Step 2: Convert to fraction form
    81.88/121.98 = 79.76/x
  3. Step 3: Cross multiply
    81.88x = 121.98 × 79.76
  4. Step 4: Simplify right side
    81.88x = 9,729.12
  5. Step 5: Solve for x
    x = 9,729.12/81.88
  6. Step 6: Final answer
    x = 118.82

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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.