Finding the Fourth Proportional to 128,731.43, 177,659.85 and 71,388.72

Step by Step Solution

1. Step 1: Write the proportion equation
   128,731.43 : 177,659.85 = 71,388.72 : x
2. Step 2: Convert to fraction form
   128,731.43/177,659.85 = 71,388.72/x
3. Step 3: Cross multiply
   128,731.43x = 177,659.85 × 71,388.72
4. Step 4: Simplify right side
   128,731.43x = 12,682,909,286.89
5. Step 5: Solve for x
   x = 12,682,909,286.89/128,731.43
6. Step 6: Final answer
   x = 98,522.25