Finding the Fourth Proportional to 12,279.31, 18,421.59 and 3,959.80

Step by Step Solution

1. Step 1: Write the proportion equation
   12,279.31 : 18,421.59 = 3,959.80 : x
2. Step 2: Convert to fraction form
   12,279.31/18,421.59 = 3,959.80/x
3. Step 3: Cross multiply
   12,279.31x = 18,421.59 × 3,959.80
4. Step 4: Simplify right side
   12,279.31x = 72,945,812.08
5. Step 5: Solve for x
   x = 72,945,812.08/12,279.31
6. Step 6: Final answer
   x = 5,940.55