Finding the Fourth Proportional to 1,805.28, 2,487.72 and 1,280.40

Step by Step Solution

1. Step 1: Write the proportion equation
   1,805.28 : 2,487.72 = 1,280.40 : x
2. Step 2: Convert to fraction form
   1,805.28/2,487.72 = 1,280.40/x
3. Step 3: Cross multiply
   1,805.28x = 2,487.72 × 1,280.40
4. Step 4: Simplify right side
   1,805.28x = 3,185,276.69
5. Step 5: Solve for x
   x = 3,185,276.69/1,805.28
6. Step 6: Final answer
   x = 1,764.42