Finding the Fourth Proportional to 81,078.77, 111,789.42 and 66,688.31

Step by Step Solution

1. Step 1: Write the proportion equation
   81,078.77 : 111,789.42 = 66,688.31 : x
2. Step 2: Convert to fraction form
   81,078.77/111,789.42 = 66,688.31/x
3. Step 3: Cross multiply
   81,078.77x = 111,789.42 × 66,688.31
4. Step 4: Simplify right side
   81,078.77x = 7,455,047,525.07
5. Step 5: Solve for x
   x = 7,455,047,525.07/81,078.77
6. Step 6: Final answer
   x = 91,948.20