Finding the Fourth Proportional to 1,216.50, 1,678.64 and 685.37

Step by Step Solution

1. Step 1: Write the proportion equation
   1,216.50 : 1,678.64 = 685.37 : x
2. Step 2: Convert to fraction form
   1,216.50/1,678.64 = 685.37/x
3. Step 3: Cross multiply
   1,216.50x = 1,678.64 × 685.37
4. Step 4: Simplify right side
   1,216.50x = 1,150,486.52
5. Step 5: Solve for x
   x = 1,150,486.52/1,216.50
6. Step 6: Final answer
   x = 945.74