Finding the Fourth Proportional to 91,141.68, 136,931.76 and 86,106.72

Step by Step Solution

1. Step 1: Write the proportion equation
   91,141.68 : 136,931.76 = 86,106.72 : x
2. Step 2: Convert to fraction form
   91,141.68/136,931.76 = 86,106.72/x
3. Step 3: Cross multiply
   91,141.68x = 136,931.76 × 86,106.72
4. Step 4: Simplify right side
   91,141.68x = 11,790,744,717.43
5. Step 5: Solve for x
   x = 11,790,744,717.43/91,141.68
6. Step 6: Final answer
   x = 129,367.21