Finding the Fourth Proportional to 1,080.91, 1,491.78 and 688.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,080.91 : 1,491.78 = 688.15 : x
2. Step 2: Convert to fraction form
   1,080.91/1,491.78 = 688.15/x
3. Step 3: Cross multiply
   1,080.91x = 1,491.78 × 688.15
4. Step 4: Simplify right side
   1,080.91x = 1,026,568.41
5. Step 5: Solve for x
   x = 1,026,568.41/1,080.91
6. Step 6: Final answer
   x = 949.73