Finding the Fourth Proportional to 99.12, 147.89 and 86.27

Step by Step Solution

1. Step 1: Write the proportion equation
   99.12 : 147.89 = 86.27 : x
2. Step 2: Convert to fraction form
   99.12/147.89 = 86.27/x
3. Step 3: Cross multiply
   99.12x = 147.89 × 86.27
4. Step 4: Simplify right side
   99.12x = 12,757.95
5. Step 5: Solve for x
   x = 12,757.95/99.12
6. Step 6: Final answer
   x = 128.71