Finding the Fourth Proportional to 21,165.57, 31,725.97 and 7,830

Step by Step Solution

1. Step 1: Write the proportion equation
   21,165.57 : 31,725.97 = 7,830 : x
2. Step 2: Convert to fraction form
   21,165.57/31,725.97 = 7,830/x
3. Step 3: Cross multiply
   21,165.57x = 31,725.97 × 7,830
4. Step 4: Simplify right side
   21,165.57x = 248,414,345.10
5. Step 5: Solve for x
   x = 248,414,345.10/21,165.57
6. Step 6: Final answer
   x = 11,736.72