Finding the Fourth Proportional to 21,323.55, 31,949.94 and 12,978.33

Step by Step Solution

1. Step 1: Write the proportion equation
   21,323.55 : 31,949.94 = 12,978.33 : x
2. Step 2: Convert to fraction form
   21,323.55/31,949.94 = 12,978.33/x
3. Step 3: Cross multiply
   21,323.55x = 31,949.94 × 12,978.33
4. Step 4: Simplify right side
   21,323.55x = 414,656,793.66
5. Step 5: Solve for x
   x = 414,656,793.66/21,323.55
6. Step 6: Final answer
   x = 19,445.95