Finding the Fourth Proportional to 127.39, 191.12 and 86.42

Step by Step Solution

1. Step 1: Write the proportion equation
   127.39 : 191.12 = 86.42 : x
2. Step 2: Convert to fraction form
   127.39/191.12 = 86.42/x
3. Step 3: Cross multiply
   127.39x = 191.12 × 86.42
4. Step 4: Simplify right side
   127.39x = 16,516.59
5. Step 5: Solve for x
   x = 16,516.59/127.39
6. Step 6: Final answer
   x = 129.65