Finding the Fourth Proportional to 20,978.79, 31,511.94 and 12,230.79

Step by Step Solution

1. Step 1: Write the proportion equation
   20,978.79 : 31,511.94 = 12,230.79 : x
2. Step 2: Convert to fraction form
   20,978.79/31,511.94 = 12,230.79/x
3. Step 3: Cross multiply
   20,978.79x = 31,511.94 × 12,230.79
4. Step 4: Simplify right side
   20,978.79x = 385,415,920.63
5. Step 5: Solve for x
   x = 385,415,920.63/20,978.79
6. Step 6: Final answer
   x = 18,371.69