Finding the Fourth Proportional to 91,772.10, 128,218.50 and 91,772.10

Step by Step Solution

1. Step 1: Write the proportion equation
   91,772.10 : 128,218.50 = 91,772.10 : x
2. Step 2: Convert to fraction form
   91,772.10/128,218.50 = 91,772.10/x
3. Step 3: Cross multiply
   91,772.10x = 128,218.50 × 91,772.10
4. Step 4: Simplify right side
   91,772.10x = 11,766,881,003.85
5. Step 5: Solve for x
   x = 11,766,881,003.85/91,772.10
6. Step 6: Final answer
   x = 128,218.50