Finding the Fourth Proportional to 128.52, 177.30 and 100.89

Step by Step Solution

1. Step 1: Write the proportion equation
   128.52 : 177.30 = 100.89 : x
2. Step 2: Convert to fraction form
   128.52/177.30 = 100.89/x
3. Step 3: Cross multiply
   128.52x = 177.30 × 100.89
4. Step 4: Simplify right side
   128.52x = 17,887.80
5. Step 5: Solve for x
   x = 17,887.80/128.52
6. Step 6: Final answer
   x = 139.18