Finding the Fourth Proportional to 91,892.90, 128,912.50 and 91,892.90

Step by Step Solution

1. Step 1: Write the proportion equation
   91,892.90 : 128,912.50 = 91,892.90 : x
2. Step 2: Convert to fraction form
   91,892.90/128,912.50 = 91,892.90/x
3. Step 3: Cross multiply
   91,892.90x = 128,912.50 × 91,892.90
4. Step 4: Simplify right side
   91,892.90x = 11,846,143,471.25
5. Step 5: Solve for x
   x = 11,846,143,471.25/91,892.90
6. Step 6: Final answer
   x = 128,912.50