Finding the Fourth Proportional to 86,065.76, 128,233.60 and 81,231.31

Step by Step Solution

1. Step 1: Write the proportion equation
   86,065.76 : 128,233.60 = 81,231.31 : x
2. Step 2: Convert to fraction form
   86,065.76/128,233.60 = 81,231.31/x
3. Step 3: Cross multiply
   86,065.76x = 128,233.60 × 81,231.31
4. Step 4: Simplify right side
   86,065.76x = 10,416,583,314.02
5. Step 5: Solve for x
   x = 10,416,583,314.02/86,065.76
6. Step 6: Final answer
   x = 121,030.52