Finding the Fourth Proportional to 128.72, 193.10 and 55.59

Step by Step Solution

1. Step 1: Write the proportion equation
   128.72 : 193.10 = 55.59 : x
2. Step 2: Convert to fraction form
   128.72/193.10 = 55.59/x
3. Step 3: Cross multiply
   128.72x = 193.10 × 55.59
4. Step 4: Simplify right side
   128.72x = 10,734.15
5. Step 5: Solve for x
   x = 10,734.15/128.72
6. Step 6: Final answer
   x = 83.39