Finding the Fourth Proportional to 21,007.89, 28,989.77 and 12,058.20

Step by Step Solution

1. Step 1: Write the proportion equation
   21,007.89 : 28,989.77 = 12,058.20 : x
2. Step 2: Convert to fraction form
   21,007.89/28,989.77 = 12,058.20/x
3. Step 3: Cross multiply
   21,007.89x = 28,989.77 × 12,058.20
4. Step 4: Simplify right side
   21,007.89x = 349,564,384.32
5. Step 5: Solve for x
   x = 349,564,384.32/21,007.89
6. Step 6: Final answer
   x = 16,639.67