Finding the Fourth Proportional to 131.60, 196.96 and 128.12

Step by Step Solution

1. Step 1: Write the proportion equation
   131.60 : 196.96 = 128.12 : x
2. Step 2: Convert to fraction form
   131.60/196.96 = 128.12/x
3. Step 3: Cross multiply
   131.60x = 196.96 × 128.12
4. Step 4: Simplify right side
   131.60x = 25,234.52
5. Step 5: Solve for x
   x = 25,234.52/131.60
6. Step 6: Final answer
   x = 191.75