Finding the Fourth Proportional to 21,111.84, 31,669.20 and 7,961.76

Step by Step Solution

1. Step 1: Write the proportion equation
   21,111.84 : 31,669.20 = 7,961.76 : x
2. Step 2: Convert to fraction form
   21,111.84/31,669.20 = 7,961.76/x
3. Step 3: Cross multiply
   21,111.84x = 31,669.20 × 7,961.76
4. Step 4: Simplify right side
   21,111.84x = 252,142,569.79
5. Step 5: Solve for x
   x = 252,142,569.79/21,111.84
6. Step 6: Final answer
   x = 11,943.18