Finding the Fourth Proportional to 89.15, 122.81 and 72.72

Step by Step Solution

1. Step 1: Write the proportion equation
   89.15 : 122.81 = 72.72 : x
2. Step 2: Convert to fraction form
   89.15/122.81 = 72.72/x
3. Step 3: Cross multiply
   89.15x = 122.81 × 72.72
4. Step 4: Simplify right side
   89.15x = 8,930.38
5. Step 5: Solve for x
   x = 8,930.38/89.15
6. Step 6: Final answer
   x = 100.18