Finding the Fourth Proportional to 1,216.56, 1,678.82 and 685.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,216.56 : 1,678.82 = 685.50 : x
2. Step 2: Convert to fraction form
   1,216.56/1,678.82 = 685.50/x
3. Step 3: Cross multiply
   1,216.56x = 1,678.82 × 685.50
4. Step 4: Simplify right side
   1,216.56x = 1,150,827.68
5. Step 5: Solve for x
   x = 1,150,827.68/1,216.56
6. Step 6: Final answer
   x = 945.97