Finding the Fourth Proportional to 91,709.30, 128,480.50 and 91,709.30

Step by Step Solution

1. Step 1: Write the proportion equation
   91,709.30 : 128,480.50 = 91,709.30 : x
2. Step 2: Convert to fraction form
   91,709.30/128,480.50 = 91,709.30/x
3. Step 3: Cross multiply
   91,709.30x = 128,480.50 × 91,709.30
4. Step 4: Simplify right side
   91,709.30x = 11,782,856,718.65
5. Step 5: Solve for x
   x = 11,782,856,718.65/91,709.30
6. Step 6: Final answer
   x = 128,480.50