Finding the Fourth Proportional to 1,086.84, 1,499.74 and 644.68

Step by Step Solution

1. Step 1: Write the proportion equation
   1,086.84 : 1,499.74 = 644.68 : x
2. Step 2: Convert to fraction form
   1,086.84/1,499.74 = 644.68/x
3. Step 3: Cross multiply
   1,086.84x = 1,499.74 × 644.68
4. Step 4: Simplify right side
   1,086.84x = 966,852.38
5. Step 5: Solve for x
   x = 966,852.38/1,086.84
6. Step 6: Final answer
   x = 889.60