Finding the Fourth Proportional to 86.27, 128.72 and 84.29

Step by Step Solution

1. Step 1: Write the proportion equation
   86.27 : 128.72 = 84.29 : x
2. Step 2: Convert to fraction form
   86.27/128.72 = 84.29/x
3. Step 3: Cross multiply
   86.27x = 128.72 × 84.29
4. Step 4: Simplify right side
   86.27x = 10,849.38
5. Step 5: Solve for x
   x = 10,849.38/86.27
6. Step 6: Final answer
   x = 125.77