Finding the Fourth Proportional to 21,477.52, 29,639.31 and 12,978.46

Step by Step Solution

1. Step 1: Write the proportion equation
   21,477.52 : 29,639.31 = 12,978.46 : x
2. Step 2: Convert to fraction form
   21,477.52/29,639.31 = 12,978.46/x
3. Step 3: Cross multiply
   21,477.52x = 29,639.31 × 12,978.46
4. Step 4: Simplify right side
   21,477.52x = 384,672,599.26
5. Step 5: Solve for x
   x = 384,672,599.26/21,477.52
6. Step 6: Final answer
   x = 17,910.48