Finding the Third Proportional to 118.88 and 128.69

Step by Step Solution

1. Step 1: Write the proportion equation
   118.88 : 128.69 = 128.69 : x
2. Step 2: Convert to fraction form
   118.88/128.69 = 128.69/x
3. Step 3: Cross multiply
   118.88x = 128.69 × 128.69
4. Step 4: Simplify right side
   118.88x = 16,560.47
5. Step 5: Solve for x
   x = 16,560.47/118.88
6. Step 6: Final answer
   x = 139.31