Finding the Fourth Proportional to 1,086.65, 1,499.06 and 644.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,086.65 : 1,499.06 = 644.55 : x
2. Step 2: Convert to fraction form
   1,086.65/1,499.06 = 644.55/x
3. Step 3: Cross multiply
   1,086.65x = 1,499.06 × 644.55
4. Step 4: Simplify right side
   1,086.65x = 966,215.90
5. Step 5: Solve for x
   x = 966,215.90/1,086.65
6. Step 6: Final answer
   x = 889.17