Finding the Fourth Proportional to 1,080.72, 1,490.94 and 687.64

Step by Step Solution

1. Step 1: Write the proportion equation
   1,080.72 : 1,490.94 = 687.64 : x
2. Step 2: Convert to fraction form
   1,080.72/1,490.94 = 687.64/x
3. Step 3: Cross multiply
   1,080.72x = 1,490.94 × 687.64
4. Step 4: Simplify right side
   1,080.72x = 1,025,229.98
5. Step 5: Solve for x
   x = 1,025,229.98/1,080.72
6. Step 6: Final answer
   x = 948.65