Finding the Fourth Proportional to 99.67, 149.56 and 86.05

Step by Step Solution

1. Step 1: Write the proportion equation
   99.67 : 149.56 = 86.05 : x
2. Step 2: Convert to fraction form
   99.67/149.56 = 86.05/x
3. Step 3: Cross multiply
   99.67x = 149.56 × 86.05
4. Step 4: Simplify right side
   99.67x = 12,869.56
5. Step 5: Solve for x
   x = 12,869.56/99.67
6. Step 6: Final answer
   x = 129.12