Finding the Fourth Proportional to 128.72, 177.59 and 76.25

Step by Step Solution

1. Step 1: Write the proportion equation
   128.72 : 177.59 = 76.25 : x
2. Step 2: Convert to fraction form
   128.72/177.59 = 76.25/x
3. Step 3: Cross multiply
   128.72x = 177.59 × 76.25
4. Step 4: Simplify right side
   128.72x = 13,540.79
5. Step 5: Solve for x
   x = 13,540.79/128.72
6. Step 6: Final answer
   x = 105.20