Finding the Fourth Proportional to 21,111.59, 31,613.81 and 12,672.85

Step by Step Solution

1. Step 1: Write the proportion equation
   21,111.59 : 31,613.81 = 12,672.85 : x
2. Step 2: Convert to fraction form
   21,111.59/31,613.81 = 12,672.85/x
3. Step 3: Cross multiply
   21,111.59x = 31,613.81 × 12,672.85
4. Step 4: Simplify right side
   21,111.59x = 400,637,024.71
5. Step 5: Solve for x
   x = 400,637,024.71/21,111.59
6. Step 6: Final answer
   x = 18,977.11