Finding the Fourth Proportional to 129,084.69, 178,139.16 and 71,729.31

Step by Step Solution

1. Step 1: Write the proportion equation
   129,084.69 : 178,139.16 = 71,729.31 : x
2. Step 2: Convert to fraction form
   129,084.69/178,139.16 = 71,729.31/x
3. Step 3: Cross multiply
   129,084.69x = 178,139.16 × 71,729.31
4. Step 4: Simplify right side
   129,084.69x = 12,777,799,030.78
5. Step 5: Solve for x
   x = 12,777,799,030.78/129,084.69
6. Step 6: Final answer
   x = 98,987.72