Finding the Fourth Proportional to 1,223.61, 1,689.17 and 699.54

Step by Step Solution

1. Step 1: Write the proportion equation
   1,223.61 : 1,689.17 = 699.54 : x
2. Step 2: Convert to fraction form
   1,223.61/1,689.17 = 699.54/x
3. Step 3: Cross multiply
   1,223.61x = 1,689.17 × 699.54
4. Step 4: Simplify right side
   1,223.61x = 1,181,638.48
5. Step 5: Solve for x
   x = 1,181,638.48/1,223.61
6. Step 6: Final answer
   x = 965.70