Finding the Fourth Proportional to 89.01, 122.85 and 81.72

Step by Step Solution

1. Step 1: Write the proportion equation
   89.01 : 122.85 = 81.72 : x
2. Step 2: Convert to fraction form
   89.01/122.85 = 81.72/x
3. Step 3: Cross multiply
   89.01x = 122.85 × 81.72
4. Step 4: Simplify right side
   89.01x = 10,039.30
5. Step 5: Solve for x
   x = 10,039.30/89.01
6. Step 6: Final answer
   x = 112.79