Finding the Fourth Proportional to 80.98, 111.31 and 72.61

Step by Step Solution

1. Step 1: Write the proportion equation
   80.98 : 111.31 = 72.61 : x
2. Step 2: Convert to fraction form
   80.98/111.31 = 72.61/x
3. Step 3: Cross multiply
   80.98x = 111.31 × 72.61
4. Step 4: Simplify right side
   80.98x = 8,082.40
5. Step 5: Solve for x
   x = 8,082.40/80.98
6. Step 6: Final answer
   x = 99.81