Finding the Fourth Proportional to 1,280.61, 1,767.83 and 1,139.67

Step by Step Solution

1. Step 1: Write the proportion equation
   1,280.61 : 1,767.83 = 1,139.67 : x
2. Step 2: Convert to fraction form
   1,280.61/1,767.83 = 1,139.67/x
3. Step 3: Cross multiply
   1,280.61x = 1,767.83 × 1,139.67
4. Step 4: Simplify right side
   1,280.61x = 2,014,737.12
5. Step 5: Solve for x
   x = 2,014,737.12/1,280.61
6. Step 6: Final answer
   x = 1,573.26