Finding the Fourth Proportional to 85,899.96, 128,152.46 and 81,249.86

Step by Step Solution

1. Step 1: Write the proportion equation
   85,899.96 : 128,152.46 = 81,249.86 : x
2. Step 2: Convert to fraction form
   85,899.96/128,152.46 = 81,249.86/x
3. Step 3: Cross multiply
   85,899.96x = 128,152.46 × 81,249.86
4. Step 4: Simplify right side
   85,899.96x = 10,412,368,792.89
5. Step 5: Solve for x
   x = 10,412,368,792.89/85,899.96
6. Step 6: Final answer
   x = 121,215.06