Finding the Fourth Proportional to 128.76, 192.25 and 105.86

Step by Step Solution

1. Step 1: Write the proportion equation
   128.76 : 192.25 = 105.86 : x
2. Step 2: Convert to fraction form
   128.76/192.25 = 105.86/x
3. Step 3: Cross multiply
   128.76x = 192.25 × 105.86
4. Step 4: Simplify right side
   128.76x = 20,351.59
5. Step 5: Solve for x
   x = 20,351.59/128.76
6. Step 6: Final answer
   x = 158.06