Finding the Fourth Proportional to 128,713.72, 177,629.74 and 72,123

Step by Step Solution

1. Step 1: Write the proportion equation
   128,713.72 : 177,629.74 = 72,123 : x
2. Step 2: Convert to fraction form
   128,713.72/177,629.74 = 72,123/x
3. Step 3: Cross multiply
   128,713.72x = 177,629.74 × 72,123
4. Step 4: Simplify right side
   128,713.72x = 12,811,189,738.02
5. Step 5: Solve for x
   x = 12,811,189,738.02/128,713.72
6. Step 6: Final answer
   x = 99,532.43