Finding the Fourth Proportional to 128,776.48, 177,711.78 and 72,187.72

Step by Step Solution

1. Step 1: Write the proportion equation
   128,776.48 : 177,711.78 = 72,187.72 : x
2. Step 2: Convert to fraction form
   128,776.48/177,711.78 = 72,187.72/x
3. Step 3: Cross multiply
   128,776.48x = 177,711.78 × 72,187.72
4. Step 4: Simplify right side
   128,776.48x = 12,828,608,215.34
5. Step 5: Solve for x
   x = 12,828,608,215.34/128,776.48
6. Step 6: Final answer
   x = 99,619.19