Finding the Fourth Proportional to 1,081.06, 1,490.79 and 688.30

Step by Step Solution

1. Step 1: Write the proportion equation
   1,081.06 : 1,490.79 = 688.30 : x
2. Step 2: Convert to fraction form
   1,081.06/1,490.79 = 688.30/x
3. Step 3: Cross multiply
   1,081.06x = 1,490.79 × 688.30
4. Step 4: Simplify right side
   1,081.06x = 1,026,110.76
5. Step 5: Solve for x
   x = 1,026,110.76/1,081.06
6. Step 6: Final answer
   x = 949.17