Finding the Fourth Proportional to 39,871.12, 55,021.89 and 21,965.71

Step by Step Solution

1. Step 1: Write the proportion equation
   39,871.12 : 55,021.89 = 21,965.71 : x
2. Step 2: Convert to fraction form
   39,871.12/55,021.89 = 21,965.71/x
3. Step 3: Cross multiply
   39,871.12x = 55,021.89 × 21,965.71
4. Step 4: Simplify right side
   39,871.12x = 1,208,594,879.39
5. Step 5: Solve for x
   x = 1,208,594,879.39/39,871.12
6. Step 6: Final answer
   x = 30,312.54