Finding the Fourth Proportional to 258,639.06, 387,861.78 and 90,116.12

Step by Step Solution

1. Step 1: Write the proportion equation
   258,639.06 : 387,861.78 = 90,116.12 : x
2. Step 2: Convert to fraction form
   258,639.06/387,861.78 = 90,116.12/x
3. Step 3: Cross multiply
   258,639.06x = 387,861.78 × 90,116.12
4. Step 4: Simplify right side
   258,639.06x = 34,952,598,709.89
5. Step 5: Solve for x
   x = 34,952,598,709.89/258,639.06
6. Step 6: Final answer
   x = 135,140.45