Finding the Fourth Proportional to 311.31, 466.71 and 128.60

Step by Step Solution

1. Step 1: Write the proportion equation
   311.31 : 466.71 = 128.60 : x
2. Step 2: Convert to fraction form
   311.31/466.71 = 128.60/x
3. Step 3: Cross multiply
   311.31x = 466.71 × 128.60
4. Step 4: Simplify right side
   311.31x = 60,016.57
5. Step 5: Solve for x
   x = 60,016.57/311.31
6. Step 6: Final answer
   x = 192.79