Finding the Fourth Proportional to 1,086.10, 1,499.12 and 644.25

Step by Step Solution

1. Step 1: Write the proportion equation
   1,086.10 : 1,499.12 = 644.25 : x
2. Step 2: Convert to fraction form
   1,086.10/1,499.12 = 644.25/x
3. Step 3: Cross multiply
   1,086.10x = 1,499.12 × 644.25
4. Step 4: Simplify right side
   1,086.10x = 965,808.06
5. Step 5: Solve for x
   x = 965,808.06/1,086.10
6. Step 6: Final answer
   x = 889.24