Finding the Fourth Proportional to 2,669.80, 4,005.12 and 820.72

Step by Step Solution

1. Step 1: Write the proportion equation
   2,669.80 : 4,005.12 = 820.72 : x
2. Step 2: Convert to fraction form
   2,669.80/4,005.12 = 820.72/x
3. Step 3: Cross multiply
   2,669.80x = 4,005.12 × 820.72
4. Step 4: Simplify right side
   2,669.80x = 3,287,082.09
5. Step 5: Solve for x
   x = 3,287,082.09/2,669.80
6. Step 6: Final answer
   x = 1,231.21