Finding the Fourth Proportional to 21,142.28, 31,704.78 and 7,288.04

Step by Step Solution

1. Step 1: Write the proportion equation
   21,142.28 : 31,704.78 = 7,288.04 : x
2. Step 2: Convert to fraction form
   21,142.28/31,704.78 = 7,288.04/x
3. Step 3: Cross multiply
   21,142.28x = 31,704.78 × 7,288.04
4. Step 4: Simplify right side
   21,142.28x = 231,065,704.83
5. Step 5: Solve for x
   x = 231,065,704.83/21,142.28
6. Step 6: Final answer
   x = 10,929.08