Finding the Fourth Proportional to 2,643.12, 3,959.37 and 1,257.78

Step by Step Solution

1. Step 1: Write the proportion equation
   2,643.12 : 3,959.37 = 1,257.78 : x
2. Step 2: Convert to fraction form
   2,643.12/3,959.37 = 1,257.78/x
3. Step 3: Cross multiply
   2,643.12x = 3,959.37 × 1,257.78
4. Step 4: Simplify right side
   2,643.12x = 4,980,016.40
5. Step 5: Solve for x
   x = 4,980,016.40/2,643.12
6. Step 6: Final answer
   x = 1,884.14