Finding the Fourth Proportional to 109,100.40, 163,731.72 and 81,085.68

Step by Step Solution

1. Step 1: Write the proportion equation
   109,100.40 : 163,731.72 = 81,085.68 : x
2. Step 2: Convert to fraction form
   109,100.40/163,731.72 = 81,085.68/x
3. Step 3: Cross multiply
   109,100.40x = 163,731.72 × 81,085.68
4. Step 4: Simplify right side
   109,100.40x = 13,276,297,853.77
5. Step 5: Solve for x
   x = 13,276,297,853.77/109,100.40
6. Step 6: Final answer
   x = 121,688.81