Finding the Fourth Proportional to 21,128.52, 31,699.74 and 7,982.04

Step by Step Solution

1. Step 1: Write the proportion equation
   21,128.52 : 31,699.74 = 7,982.04 : x
2. Step 2: Convert to fraction form
   21,128.52/31,699.74 = 7,982.04/x
3. Step 3: Cross multiply
   21,128.52x = 31,699.74 × 7,982.04
4. Step 4: Simplify right side
   21,128.52x = 253,028,592.67
5. Step 5: Solve for x
   x = 253,028,592.67/21,128.52
6. Step 6: Final answer
   x = 11,975.69