Finding the Fourth Proportional to 2,215.72, 3,322.78 and 809.76

Step by Step Solution

1. Step 1: Write the proportion equation
   2,215.72 : 3,322.78 = 809.76 : x
2. Step 2: Convert to fraction form
   2,215.72/3,322.78 = 809.76/x
3. Step 3: Cross multiply
   2,215.72x = 3,322.78 × 809.76
4. Step 4: Simplify right side
   2,215.72x = 2,690,654.33
5. Step 5: Solve for x
   x = 2,690,654.33/2,215.72
6. Step 6: Final answer
   x = 1,214.35