Finding the Fourth Proportional to 1,086.27, 1,499.40 and 644.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,086.27 : 1,499.40 = 644.31 : x
2. Step 2: Convert to fraction form
   1,086.27/1,499.40 = 644.31/x
3. Step 3: Cross multiply
   1,086.27x = 1,499.40 × 644.31
4. Step 4: Simplify right side
   1,086.27x = 966,078.41
5. Step 5: Solve for x
   x = 966,078.41/1,086.27
6. Step 6: Final answer
   x = 889.35