Finding the Fourth Proportional to 1,978.78, 2,730.66 and 1,280.56

Step by Step Solution

1. Step 1: Write the proportion equation
   1,978.78 : 2,730.66 = 1,280.56 : x
2. Step 2: Convert to fraction form
   1,978.78/2,730.66 = 1,280.56/x
3. Step 3: Cross multiply
   1,978.78x = 2,730.66 × 1,280.56
4. Step 4: Simplify right side
   1,978.78x = 3,496,773.97
5. Step 5: Solve for x
   x = 3,496,773.97/1,978.78
6. Step 6: Final answer
   x = 1,767.14