Finding the Fourth Proportional to 128.15, 176.82 and 72.89

Step by Step Solution

1. Step 1: Write the proportion equation
   128.15 : 176.82 = 72.89 : x
2. Step 2: Convert to fraction form
   128.15/176.82 = 72.89/x
3. Step 3: Cross multiply
   128.15x = 176.82 × 72.89
4. Step 4: Simplify right side
   128.15x = 12,887.53
5. Step 5: Solve for x
   x = 12,887.53/128.15
6. Step 6: Final answer
   x = 100.57