Finding the Fourth Proportional to 128,775.48, 177,710.40 and 72,186.72

Step by Step Solution

1. Step 1: Write the proportion equation
   128,775.48 : 177,710.40 = 72,186.72 : x
2. Step 2: Convert to fraction form
   128,775.48/177,710.40 = 72,186.72/x
3. Step 3: Cross multiply
   128,775.48x = 177,710.40 × 72,186.72
4. Step 4: Simplify right side
   128,775.48x = 12,828,330,885.89
5. Step 5: Solve for x
   x = 12,828,330,885.89/128,775.48
6. Step 6: Final answer
   x = 99,617.81