Finding the Fourth Proportional to 1,223.07, 1,687.42 and 691.89

Step by Step Solution

1. Step 1: Write the proportion equation
   1,223.07 : 1,687.42 = 691.89 : x
2. Step 2: Convert to fraction form
   1,223.07/1,687.42 = 691.89/x
3. Step 3: Cross multiply
   1,223.07x = 1,687.42 × 691.89
4. Step 4: Simplify right side
   1,223.07x = 1,167,509.89
5. Step 5: Solve for x
   x = 1,167,509.89/1,223.07
6. Step 6: Final answer
   x = 954.57