Finding the Fourth Proportional to 128.88, 193.17 and 55.72

Step by Step Solution

1. Step 1: Write the proportion equation
   128.88 : 193.17 = 55.72 : x
2. Step 2: Convert to fraction form
   128.88/193.17 = 55.72/x
3. Step 3: Cross multiply
   128.88x = 193.17 × 55.72
4. Step 4: Simplify right side
   128.88x = 10,763.88
5. Step 5: Solve for x
   x = 10,763.88/128.88
6. Step 6: Final answer
   x = 83.52