Finding the Fourth Proportional to 86.01, 128.81 and 71.43

Step by Step Solution

1. Step 1: Write the proportion equation
   86.01 : 128.81 = 71.43 : x
2. Step 2: Convert to fraction form
   86.01/128.81 = 71.43/x
3. Step 3: Cross multiply
   86.01x = 128.81 × 71.43
4. Step 4: Simplify right side
   86.01x = 9,200.54
5. Step 5: Solve for x
   x = 9,200.54/86.01
6. Step 6: Final answer
   x = 106.97