Finding the Fourth Proportional to 1,086.30, 1,499.12 and 644.13

Step by Step Solution

1. Step 1: Write the proportion equation
   1,086.30 : 1,499.12 = 644.13 : x
2. Step 2: Convert to fraction form
   1,086.30/1,499.12 = 644.13/x
3. Step 3: Cross multiply
   1,086.30x = 1,499.12 × 644.13
4. Step 4: Simplify right side
   1,086.30x = 965,628.17
5. Step 5: Solve for x
   x = 965,628.17/1,086.30
6. Step 6: Final answer
   x = 888.91