Finding the Fourth Proportional to 128.89, 177.89 and 76.48

Step by Step Solution

1. Step 1: Write the proportion equation
   128.89 : 177.89 = 76.48 : x
2. Step 2: Convert to fraction form
   128.89/177.89 = 76.48/x
3. Step 3: Cross multiply
   128.89x = 177.89 × 76.48
4. Step 4: Simplify right side
   128.89x = 13,605.74
5. Step 5: Solve for x
   x = 13,605.74/128.89
6. Step 6: Final answer
   x = 105.56