Finding the Fourth Proportional to 1,086.57, 1,499.54 and 644.49

Step by Step Solution

1. Step 1: Write the proportion equation
   1,086.57 : 1,499.54 = 644.49 : x
2. Step 2: Convert to fraction form
   1,086.57/1,499.54 = 644.49/x
3. Step 3: Cross multiply
   1,086.57x = 1,499.54 × 644.49
4. Step 4: Simplify right side
   1,086.57x = 966,435.31
5. Step 5: Solve for x
   x = 966,435.31/1,086.57
6. Step 6: Final answer
   x = 889.44