Finding the Fourth Proportional to 128.09, 176.78 and 72.83

Step by Step Solution

1. Step 1: Write the proportion equation
   128.09 : 176.78 = 72.83 : x
2. Step 2: Convert to fraction form
   128.09/176.78 = 72.83/x
3. Step 3: Cross multiply
   128.09x = 176.78 × 72.83
4. Step 4: Simplify right side
   128.09x = 12,874.89
5. Step 5: Solve for x
   x = 12,874.89/128.09
6. Step 6: Final answer
   x = 100.51