Finding the Fourth Proportional to 1,086.86, 1,499.67 and 644.87

Step by Step Solution

1. Step 1: Write the proportion equation
   1,086.86 : 1,499.67 = 644.87 : x
2. Step 2: Convert to fraction form
   1,086.86/1,499.67 = 644.87/x
3. Step 3: Cross multiply
   1,086.86x = 1,499.67 × 644.87
4. Step 4: Simplify right side
   1,086.86x = 967,084.69
5. Step 5: Solve for x
   x = 967,084.69/1,086.86
6. Step 6: Final answer
   x = 889.80