Finding the Fourth Proportional to 1,223.13, 1,687.89 and 699.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,223.13 : 1,687.89 = 699.15 : x
2. Step 2: Convert to fraction form
   1,223.13/1,687.89 = 699.15/x
3. Step 3: Cross multiply
   1,223.13x = 1,687.89 × 699.15
4. Step 4: Simplify right side
   1,223.13x = 1,180,088.29
5. Step 5: Solve for x
   x = 1,180,088.29/1,223.13
6. Step 6: Final answer
   x = 964.81