Finding the Fourth Proportional to 1,086.85, 1,499.66 and 644.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,086.85 : 1,499.66 = 644.72 : x
2. Step 2: Convert to fraction form
   1,086.85/1,499.66 = 644.72/x
3. Step 3: Cross multiply
   1,086.85x = 1,499.66 × 644.72
4. Step 4: Simplify right side
   1,086.85x = 966,860.80
5. Step 5: Solve for x
   x = 966,860.80/1,086.85
6. Step 6: Final answer
   x = 889.60