Finding the Fourth Proportional to 1,188.85, 1,640.71 and 684.87

Step by Step Solution

1. Step 1: Write the proportion equation
   1,188.85 : 1,640.71 = 684.87 : x
2. Step 2: Convert to fraction form
   1,188.85/1,640.71 = 684.87/x
3. Step 3: Cross multiply
   1,188.85x = 1,640.71 × 684.87
4. Step 4: Simplify right side
   1,188.85x = 1,123,673.06
5. Step 5: Solve for x
   x = 1,123,673.06/1,188.85
6. Step 6: Final answer
   x = 945.18