Finding the Fourth Proportional to 71,787.60, 99,066.78 and 39,959.28

Step by Step Solution

1. Step 1: Write the proportion equation
   71,787.60 : 99,066.78 = 39,959.28 : x
2. Step 2: Convert to fraction form
   71,787.60/99,066.78 = 39,959.28/x
3. Step 3: Cross multiply
   71,787.60x = 99,066.78 × 39,959.28
4. Step 4: Simplify right side
   71,787.60x = 3,958,637,200.72
5. Step 5: Solve for x
   x = 3,958,637,200.72/71,787.60
6. Step 6: Final answer
   x = 55,143.75