Finding the Fourth Proportional to 3,990.31, 5,506.72 and 2,221.88

Step by Step Solution

1. Step 1: Write the proportion equation
   3,990.31 : 5,506.72 = 2,221.88 : x
2. Step 2: Convert to fraction form
   3,990.31/5,506.72 = 2,221.88/x
3. Step 3: Cross multiply
   3,990.31x = 5,506.72 × 2,221.88
4. Step 4: Simplify right side
   3,990.31x = 12,235,237.95
5. Step 5: Solve for x
   x = 12,235,237.95/3,990.31
6. Step 6: Final answer
   x = 3,066.24