Finding the Fourth Proportional to 1,086.76, 1,499.05 and 644.34

Step by Step Solution

1. Step 1: Write the proportion equation
   1,086.76 : 1,499.05 = 644.34 : x
2. Step 2: Convert to fraction form
   1,086.76/1,499.05 = 644.34/x
3. Step 3: Cross multiply
   1,086.76x = 1,499.05 × 644.34
4. Step 4: Simplify right side
   1,086.76x = 965,900.68
5. Step 5: Solve for x
   x = 965,900.68/1,086.76
6. Step 6: Final answer
   x = 888.79