Finding the Fourth Proportional to 1,222.82, 1,687.33 and 691.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,222.82 : 1,687.33 = 691.78 : x
2. Step 2: Convert to fraction form
   1,222.82/1,687.33 = 691.78/x
3. Step 3: Cross multiply
   1,222.82x = 1,687.33 × 691.78
4. Step 4: Simplify right side
   1,222.82x = 1,167,255.20
5. Step 5: Solve for x
   x = 1,167,255.20/1,222.82
6. Step 6: Final answer
   x = 954.56