Finding the Fourth Proportional to 1,223.31, 1,688.17 and 699.36

Step by Step Solution

1. Step 1: Write the proportion equation
   1,223.31 : 1,688.17 = 699.36 : x
2. Step 2: Convert to fraction form
   1,223.31/1,688.17 = 699.36/x
3. Step 3: Cross multiply
   1,223.31x = 1,688.17 × 699.36
4. Step 4: Simplify right side
   1,223.31x = 1,180,631.88
5. Step 5: Solve for x
   x = 1,180,631.88/1,223.31
6. Step 6: Final answer
   x = 965.11