Finding the Fourth Proportional to 93.31, 128.61 and 72.61

Step by Step Solution

1. Step 1: Write the proportion equation
   93.31 : 128.61 = 72.61 : x
2. Step 2: Convert to fraction form
   93.31/128.61 = 72.61/x
3. Step 3: Cross multiply
   93.31x = 128.61 × 72.61
4. Step 4: Simplify right side
   93.31x = 9,338.05
5. Step 5: Solve for x
   x = 9,338.05/93.31
6. Step 6: Final answer
   x = 100.08