Finding the Fourth Proportional to 128,688.76, 177,590.37 and 72,100.54

Step by Step Solution

1. Step 1: Write the proportion equation
   128,688.76 : 177,590.37 = 72,100.54 : x
2. Step 2: Convert to fraction form
   128,688.76/177,590.37 = 72,100.54/x
3. Step 3: Cross multiply
   128,688.76x = 177,590.37 × 72,100.54
4. Step 4: Simplify right side
   128,688.76x = 12,804,361,575.80
5. Step 5: Solve for x
   x = 12,804,361,575.80/128,688.76
6. Step 6: Final answer
   x = 99,498.68