Finding the Fourth Proportional to 128,976.86, 177,996 and 72,388.28

Step by Step Solution

1. Step 1: Write the proportion equation
   128,976.86 : 177,996 = 72,388.28 : x
2. Step 2: Convert to fraction form
   128,976.86/177,996 = 72,388.28/x
3. Step 3: Cross multiply
   128,976.86x = 177,996 × 72,388.28
4. Step 4: Simplify right side
   128,976.86x = 12,884,824,286.88
5. Step 5: Solve for x
   x = 12,884,824,286.88/128,976.86
6. Step 6: Final answer
   x = 99,900.28