Finding the Fourth Proportional to 86,802.58, 129,991.55 and 78,388.10

Step by Step Solution

1. Step 1: Write the proportion equation
   86,802.58 : 129,991.55 = 78,388.10 : x
2. Step 2: Convert to fraction form
   86,802.58/129,991.55 = 78,388.10/x
3. Step 3: Cross multiply
   86,802.58x = 129,991.55 × 78,388.10
4. Step 4: Simplify right side
   86,802.58x = 10,189,790,228.61
5. Step 5: Solve for x
   x = 10,189,790,228.61/86,802.58
6. Step 6: Final answer
   x = 117,390.41