Finding the Fourth Proportional to 1,280.59, 1,767.40 and 721.10

Step by Step Solution

1. Step 1: Write the proportion equation
   1,280.59 : 1,767.40 = 721.10 : x
2. Step 2: Convert to fraction form
   1,280.59/1,767.40 = 721.10/x
3. Step 3: Cross multiply
   1,280.59x = 1,767.40 × 721.10
4. Step 4: Simplify right side
   1,280.59x = 1,274,474.76
5. Step 5: Solve for x
   x = 1,274,474.76/1,280.59
6. Step 6: Final answer
   x = 995.23