Finding the Fourth Proportional to 1,280.67, 1,766.93 and 721.05

Step by Step Solution

1. Step 1: Write the proportion equation
   1,280.67 : 1,766.93 = 721.05 : x
2. Step 2: Convert to fraction form
   1,280.67/1,766.93 = 721.05/x
3. Step 3: Cross multiply
   1,280.67x = 1,766.93 × 721.05
4. Step 4: Simplify right side
   1,280.67x = 1,274,041.27
5. Step 5: Solve for x
   x = 1,274,041.27/1,280.67
6. Step 6: Final answer
   x = 994.82