Finding the Fourth Proportional to 21,911.31, 30,252.20 and 12,961.68

Step by Step Solution

1. Step 1: Write the proportion equation
   21,911.31 : 30,252.20 = 12,961.68 : x
2. Step 2: Convert to fraction form
   21,911.31/30,252.20 = 12,961.68/x
3. Step 3: Cross multiply
   21,911.31x = 30,252.20 × 12,961.68
4. Step 4: Simplify right side
   21,911.31x = 392,119,270.89
5. Step 5: Solve for x
   x = 392,119,270.89/21,911.31
6. Step 6: Final answer
   x = 17,895.75