Finding the Fourth Proportional to 91,909.10, 128,410.30 and 91,909.10

Step by Step Solution

1. Step 1: Write the proportion equation
   91,909.10 : 128,410.30 = 91,909.10 : x
2. Step 2: Convert to fraction form
   91,909.10/128,410.30 = 91,909.10/x
3. Step 3: Cross multiply
   91,909.10x = 128,410.30 × 91,909.10
4. Step 4: Simplify right side
   91,909.10x = 11,802,075,103.73
5. Step 5: Solve for x
   x = 11,802,075,103.73/91,909.10
6. Step 6: Final answer
   x = 128,410.30