Finding the Fourth Proportional to 72,186.05, 99,613.89 and 39,918.57

Step by Step Solution

1. Step 1: Write the proportion equation
   72,186.05 : 99,613.89 = 39,918.57 : x
2. Step 2: Convert to fraction form
   72,186.05/99,613.89 = 39,918.57/x
3. Step 3: Cross multiply
   72,186.05x = 99,613.89 × 39,918.57
4. Step 4: Simplify right side
   72,186.05x = 3,976,444,289.97
5. Step 5: Solve for x
   x = 3,976,444,289.97/72,186.05
6. Step 6: Final answer
   x = 55,086.05