Finding the Fourth Proportional to 2,621.10, 3,930.78 and 771.78

Step by Step Solution

1. Step 1: Write the proportion equation
   2,621.10 : 3,930.78 = 771.78 : x
2. Step 2: Convert to fraction form
   2,621.10/3,930.78 = 771.78/x
3. Step 3: Cross multiply
   2,621.10x = 3,930.78 × 771.78
4. Step 4: Simplify right side
   2,621.10x = 3,033,697.39
5. Step 5: Solve for x
   x = 3,033,697.39/2,621.10
6. Step 6: Final answer
   x = 1,157.41