Finding the Fourth Proportional to 21,781.31, 32,704.76 and 12,431.88

Step by Step Solution

1. Step 1: Write the proportion equation
   21,781.31 : 32,704.76 = 12,431.88 : x
2. Step 2: Convert to fraction form
   21,781.31/32,704.76 = 12,431.88/x
3. Step 3: Cross multiply
   21,781.31x = 32,704.76 × 12,431.88
4. Step 4: Simplify right side
   21,781.31x = 406,581,682.83
5. Step 5: Solve for x
   x = 406,581,682.83/21,781.31
6. Step 6: Final answer
   x = 18,666.54