Finding the Fourth Proportional to 3,930.80, 5,412.69 and 3,398.72

Step by Step Solution

1. Step 1: Write the proportion equation
   3,930.80 : 5,412.69 = 3,398.72 : x
2. Step 2: Convert to fraction form
   3,930.80/5,412.69 = 3,398.72/x
3. Step 3: Cross multiply
   3,930.80x = 5,412.69 × 3,398.72
4. Step 4: Simplify right side
   3,930.80x = 18,396,190.69
5. Step 5: Solve for x
   x = 18,396,190.69/3,930.80
6. Step 6: Final answer
   x = 4,680.02