Finding the Fourth Proportional to 1,280.69, 1,767.33 and 721.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,280.69 : 1,767.33 = 721.15 : x
2. Step 2: Convert to fraction form
   1,280.69/1,767.33 = 721.15/x
3. Step 3: Cross multiply
   1,280.69x = 1,767.33 × 721.15
4. Step 4: Simplify right side
   1,280.69x = 1,274,510.03
5. Step 5: Solve for x
   x = 1,274,510.03/1,280.69
6. Step 6: Final answer
   x = 995.17