Finding the Fourth Proportional to 2,662.80, 3,990.90 and 1,686.72

Step by Step Solution

1. Step 1: Write the proportion equation
   2,662.80 : 3,990.90 = 1,686.72 : x
2. Step 2: Convert to fraction form
   2,662.80/3,990.90 = 1,686.72/x
3. Step 3: Cross multiply
   2,662.80x = 3,990.90 × 1,686.72
4. Step 4: Simplify right side
   2,662.80x = 6,731,530.85
5. Step 5: Solve for x
   x = 6,731,530.85/2,662.80
6. Step 6: Final answer
   x = 2,527.99