Finding the Fourth Proportional to 3,196.80, 4,377.60 and 3,139.20

Step by Step Solution

1. Step 1: Write the proportion equation
   3,196.80 : 4,377.60 = 3,139.20 : x
2. Step 2: Convert to fraction form
   3,196.80/4,377.60 = 3,139.20/x
3. Step 3: Cross multiply
   3,196.80x = 4,377.60 × 3,139.20
4. Step 4: Simplify right side
   3,196.80x = 13,742,161.92
5. Step 5: Solve for x
   x = 13,742,161.92/3,196.80
6. Step 6: Final answer
   x = 4,298.72