Finding the Fourth Proportional to 1,920.78, 2,651.06 and 1,257.39

Step by Step Solution

1. Step 1: Write the proportion equation
   1,920.78 : 2,651.06 = 1,257.39 : x
2. Step 2: Convert to fraction form
   1,920.78/2,651.06 = 1,257.39/x
3. Step 3: Cross multiply
   1,920.78x = 2,651.06 × 1,257.39
4. Step 4: Simplify right side
   1,920.78x = 3,333,419.48
5. Step 5: Solve for x
   x = 3,333,419.48/1,920.78
6. Step 6: Final answer
   x = 1,735.45