Finding the Fourth Proportional to 85,666.10, 128,499.15 and 72,706.10

Step by Step Solution

1. Step 1: Write the proportion equation
   85,666.10 : 128,499.15 = 72,706.10 : x
2. Step 2: Convert to fraction form
   85,666.10/128,499.15 = 72,706.10/x
3. Step 3: Cross multiply
   85,666.10x = 128,499.15 × 72,706.10
4. Step 4: Simplify right side
   85,666.10x = 9,342,672,049.82
5. Step 5: Solve for x
   x = 9,342,672,049.82/85,666.10
6. Step 6: Final answer
   x = 109,059.15