Finding the Fourth Proportional to 1,080.78, 1,491.03 and 688.02

Step by Step Solution

1. Step 1: Write the proportion equation
   1,080.78 : 1,491.03 = 688.02 : x
2. Step 2: Convert to fraction form
   1,080.78/1,491.03 = 688.02/x
3. Step 3: Cross multiply
   1,080.78x = 1,491.03 × 688.02
4. Step 4: Simplify right side
   1,080.78x = 1,025,858.46
5. Step 5: Solve for x
   x = 1,025,858.46/1,080.78
6. Step 6: Final answer
   x = 949.18