Finding the Fourth Proportional to 128.72, 177.72 and 111.56

Step by Step Solution

1. Step 1: Write the proportion equation
   128.72 : 177.72 = 111.56 : x
2. Step 2: Convert to fraction form
   128.72/177.72 = 111.56/x
3. Step 3: Cross multiply
   128.72x = 177.72 × 111.56
4. Step 4: Simplify right side
   128.72x = 19,826.44
5. Step 5: Solve for x
   x = 19,826.44/128.72
6. Step 6: Final answer
   x = 154.03