Finding the Fourth Proportional to 99.38, 148.64 and 86.72

Step by Step Solution

1. Step 1: Write the proportion equation
   99.38 : 148.64 = 86.72 : x
2. Step 2: Convert to fraction form
   99.38/148.64 = 86.72/x
3. Step 3: Cross multiply
   99.38x = 148.64 × 86.72
4. Step 4: Simplify right side
   99.38x = 12,889.72
5. Step 5: Solve for x
   x = 12,889.72/99.38
6. Step 6: Final answer
   x = 129.71