Finding the Fourth Proportional to 1,086.73, 1,499.46 and 644.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,086.73 : 1,499.46 = 644.78 : x
2. Step 2: Convert to fraction form
   1,086.73/1,499.46 = 644.78/x
3. Step 3: Cross multiply
   1,086.73x = 1,499.46 × 644.78
4. Step 4: Simplify right side
   1,086.73x = 966,818.07
5. Step 5: Solve for x
   x = 966,818.07/1,086.73
6. Step 6: Final answer
   x = 889.66