Finding the Fourth Proportional to 1,222.38, 1,686.78 and 698.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,222.38 : 1,686.78 = 698.31 : x
2. Step 2: Convert to fraction form
   1,222.38/1,686.78 = 698.31/x
3. Step 3: Cross multiply
   1,222.38x = 1,686.78 × 698.31
4. Step 4: Simplify right side
   1,222.38x = 1,177,895.34
5. Step 5: Solve for x
   x = 1,177,895.34/1,222.38
6. Step 6: Final answer
   x = 963.61