Finding the Fourth Proportional to 91,912.10, 128,414.50 and 91,912.10

Step by Step Solution

1. Step 1: Write the proportion equation
   91,912.10 : 128,414.50 = 91,912.10 : x
2. Step 2: Convert to fraction form
   91,912.10/128,414.50 = 91,912.10/x
3. Step 3: Cross multiply
   91,912.10x = 128,414.50 × 91,912.10
4. Step 4: Simplify right side
   91,912.10x = 11,802,846,365.45
5. Step 5: Solve for x
   x = 11,802,846,365.45/91,912.10
6. Step 6: Final answer
   x = 128,414.50