Finding the Fourth Proportional to 1,086.66, 1,499.78 and 644.81

Step by Step Solution

1. Step 1: Write the proportion equation
   1,086.66 : 1,499.78 = 644.81 : x
2. Step 2: Convert to fraction form
   1,086.66/1,499.78 = 644.81/x
3. Step 3: Cross multiply
   1,086.66x = 1,499.78 × 644.81
4. Step 4: Simplify right side
   1,086.66x = 967,067.25
5. Step 5: Solve for x
   x = 967,067.25/1,086.66
6. Step 6: Final answer
   x = 889.94