Finding the Fourth Proportional to 1,222.96, 1,687.54 and 691.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,222.96 : 1,687.54 = 691.78 : x
2. Step 2: Convert to fraction form
   1,222.96/1,687.54 = 691.78/x
3. Step 3: Cross multiply
   1,222.96x = 1,687.54 × 691.78
4. Step 4: Simplify right side
   1,222.96x = 1,167,394.52
5. Step 5: Solve for x
   x = 1,167,394.52/1,222.96
6. Step 6: Final answer
   x = 954.56