Finding the Fourth Proportional to 2,591.78, 3,887.88 and 812.72

Step by Step Solution

1. Step 1: Write the proportion equation
   2,591.78 : 3,887.88 = 812.72 : x
2. Step 2: Convert to fraction form
   2,591.78/3,887.88 = 812.72/x
3. Step 3: Cross multiply
   2,591.78x = 3,887.88 × 812.72
4. Step 4: Simplify right side
   2,591.78x = 3,159,757.83
5. Step 5: Solve for x
   x = 3,159,757.83/2,591.78
6. Step 6: Final answer
   x = 1,219.15