Finding the Fourth Proportional to 1,188.78, 1,640.41 and 684.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,188.78 : 1,640.41 = 684.50 : x
2. Step 2: Convert to fraction form
   1,188.78/1,640.41 = 684.50/x
3. Step 3: Cross multiply
   1,188.78x = 1,640.41 × 684.50
4. Step 4: Simplify right side
   1,188.78x = 1,122,849.45
5. Step 5: Solve for x
   x = 1,122,849.45/1,188.78
6. Step 6: Final answer
   x = 944.54