Finding the Fourth Proportional to 1,086.89, 1,499.65 and 644.56

Step by Step Solution

1. Step 1: Write the proportion equation
   1,086.89 : 1,499.65 = 644.56 : x
2. Step 2: Convert to fraction form
   1,086.89/1,499.65 = 644.56/x
3. Step 3: Cross multiply
   1,086.89x = 1,499.65 × 644.56
4. Step 4: Simplify right side
   1,086.89x = 966,609.04
5. Step 5: Solve for x
   x = 966,609.04/1,086.89
6. Step 6: Final answer
   x = 889.34