Finding the Fourth Proportional to 128,957.91, 177,978.31 and 72,369.28

Step by Step Solution

1. Step 1: Write the proportion equation
   128,957.91 : 177,978.31 = 72,369.28 : x
2. Step 2: Convert to fraction form
   128,957.91/177,978.31 = 72,369.28/x
3. Step 3: Cross multiply
   128,957.91x = 177,978.31 × 72,369.28
4. Step 4: Simplify right side
   128,957.91x = 12,880,162,598.94
5. Step 5: Solve for x
   x = 12,880,162,598.94/128,957.91
6. Step 6: Final answer
   x = 99,878.81