Finding the Fourth Proportional to 21,240.72, 29,304 and 13,686.48

Step by Step Solution

1. Step 1: Write the proportion equation
   21,240.72 : 29,304 = 13,686.48 : x
2. Step 2: Convert to fraction form
   21,240.72/29,304 = 13,686.48/x
3. Step 3: Cross multiply
   21,240.72x = 29,304 × 13,686.48
4. Step 4: Simplify right side
   21,240.72x = 401,068,609.92
5. Step 5: Solve for x
   x = 401,068,609.92/21,240.72
6. Step 6: Final answer
   x = 18,882.06