Finding the Fourth Proportional to 1,086.92, 1,499.52 and 644.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,086.92 : 1,499.52 = 644.78 : x
2. Step 2: Convert to fraction form
   1,086.92/1,499.52 = 644.78/x
3. Step 3: Cross multiply
   1,086.92x = 1,499.52 × 644.78
4. Step 4: Simplify right side
   1,086.92x = 966,860.51
5. Step 5: Solve for x
   x = 966,860.51/1,086.92
6. Step 6: Final answer
   x = 889.54