Finding the Fourth Proportional to 4,280.20, 6,420.12 and 2,086.72

Step by Step Solution

1. Step 1: Write the proportion equation
   4,280.20 : 6,420.12 = 2,086.72 : x
2. Step 2: Convert to fraction form
   4,280.20/6,420.12 = 2,086.72/x
3. Step 3: Cross multiply
   4,280.20x = 6,420.12 × 2,086.72
4. Step 4: Simplify right side
   4,280.20x = 13,396,992.81
5. Step 5: Solve for x
   x = 13,396,992.81/4,280.20
6. Step 6: Final answer
   x = 3,129.99