Finding the Fourth Proportional to 208,128.62, 312,066.50 and 81,617.30

Step by Step Solution

1. Step 1: Write the proportion equation
   208,128.62 : 312,066.50 = 81,617.30 : x
2. Step 2: Convert to fraction form
   208,128.62/312,066.50 = 81,617.30/x
3. Step 3: Cross multiply
   208,128.62x = 312,066.50 × 81,617.30
4. Step 4: Simplify right side
   208,128.62x = 25,470,025,150.45
5. Step 5: Solve for x
   x = 25,470,025,150.45/208,128.62
6. Step 6: Final answer
   x = 122,376.37