Finding the Fourth Proportional to 1,223.10, 1,687.88 and 663.58

Step by Step Solution

1. Step 1: Write the proportion equation
   1,223.10 : 1,687.88 = 663.58 : x
2. Step 2: Convert to fraction form
   1,223.10/1,687.88 = 663.58/x
3. Step 3: Cross multiply
   1,223.10x = 1,687.88 × 663.58
4. Step 4: Simplify right side
   1,223.10x = 1,120,033.18
5. Step 5: Solve for x
   x = 1,120,033.18/1,223.10
6. Step 6: Final answer
   x = 915.74