Finding the Fourth Proportional to 1,223.91, 1,688.86 and 699.93

Step by Step Solution

1. Step 1: Write the proportion equation
   1,223.91 : 1,688.86 = 699.93 : x
2. Step 2: Convert to fraction form
   1,223.91/1,688.86 = 699.93/x
3. Step 3: Cross multiply
   1,223.91x = 1,688.86 × 699.93
4. Step 4: Simplify right side
   1,223.91x = 1,182,083.78
5. Step 5: Solve for x
   x = 1,182,083.78/1,223.91
6. Step 6: Final answer
   x = 965.83