Finding the Fourth Proportional to 21,086.64, 29,111.67 and 13,139.46

Step by Step Solution

1. Step 1: Write the proportion equation
   21,086.64 : 29,111.67 = 13,139.46 : x
2. Step 2: Convert to fraction form
   21,086.64/29,111.67 = 13,139.46/x
3. Step 3: Cross multiply
   21,086.64x = 29,111.67 × 13,139.46
4. Step 4: Simplify right side
   21,086.64x = 382,511,623.50
5. Step 5: Solve for x
   x = 382,511,623.50/21,086.64
6. Step 6: Final answer
   x = 18,140.00