Finding the Fourth Proportional to 21,132.75, 31,697.28 and 12,810.31

Step by Step Solution

1. Step 1: Write the proportion equation
   21,132.75 : 31,697.28 = 12,810.31 : x
2. Step 2: Convert to fraction form
   21,132.75/31,697.28 = 12,810.31/x
3. Step 3: Cross multiply
   21,132.75x = 31,697.28 × 12,810.31
4. Step 4: Simplify right side
   21,132.75x = 406,052,014.98
5. Step 5: Solve for x
   x = 406,052,014.98/21,132.75
6. Step 6: Final answer
   x = 19,214.35