Finding the Fourth Proportional to 1,222.43, 1,687.05 and 691.38

Step by Step Solution

1. Step 1: Write the proportion equation
   1,222.43 : 1,687.05 = 691.38 : x
2. Step 2: Convert to fraction form
   1,222.43/1,687.05 = 691.38/x
3. Step 3: Cross multiply
   1,222.43x = 1,687.05 × 691.38
4. Step 4: Simplify right side
   1,222.43x = 1,166,389.83
5. Step 5: Solve for x
   x = 1,166,389.83/1,222.43
6. Step 6: Final answer
   x = 954.15