Finding the Fourth Proportional to 1,280.72, 1,767.30 and 721.16

Step by Step Solution

1. Step 1: Write the proportion equation
   1,280.72 : 1,767.30 = 721.16 : x
2. Step 2: Convert to fraction form
   1,280.72/1,767.30 = 721.16/x
3. Step 3: Cross multiply
   1,280.72x = 1,767.30 × 721.16
4. Step 4: Simplify right side
   1,280.72x = 1,274,506.07
5. Step 5: Solve for x
   x = 1,274,506.07/1,280.72
6. Step 6: Final answer
   x = 995.15