Finding the Fourth Proportional to 1,086.15, 1,499.33 and 644.09

Step by Step Solution

1. Step 1: Write the proportion equation
   1,086.15 : 1,499.33 = 644.09 : x
2. Step 2: Convert to fraction form
   1,086.15/1,499.33 = 644.09/x
3. Step 3: Cross multiply
   1,086.15x = 1,499.33 × 644.09
4. Step 4: Simplify right side
   1,086.15x = 965,708.82
5. Step 5: Solve for x
   x = 965,708.82/1,086.15
6. Step 6: Final answer
   x = 889.11