Finding the Fourth Proportional to 1,216.67, 1,678.94 and 685.56

Step by Step Solution

1. Step 1: Write the proportion equation
   1,216.67 : 1,678.94 = 685.56 : x
2. Step 2: Convert to fraction form
   1,216.67/1,678.94 = 685.56/x
3. Step 3: Cross multiply
   1,216.67x = 1,678.94 × 685.56
4. Step 4: Simplify right side
   1,216.67x = 1,151,020.51
5. Step 5: Solve for x
   x = 1,151,020.51/1,216.67
6. Step 6: Final answer
   x = 946.04