Finding the Fourth Proportional to 1,086.39, 1,499.04 and 644.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,086.39 : 1,499.04 = 644.31 : x
2. Step 2: Convert to fraction form
   1,086.39/1,499.04 = 644.31/x
3. Step 3: Cross multiply
   1,086.39x = 1,499.04 × 644.31
4. Step 4: Simplify right side
   1,086.39x = 965,846.46
5. Step 5: Solve for x
   x = 965,846.46/1,086.39
6. Step 6: Final answer
   x = 889.04