Finding the Fourth Proportional to 1,223.30, 1,688.15 and 663.77

Step by Step Solution

1. Step 1: Write the proportion equation
   1,223.30 : 1,688.15 = 663.77 : x
2. Step 2: Convert to fraction form
   1,223.30/1,688.15 = 663.77/x
3. Step 3: Cross multiply
   1,223.30x = 1,688.15 × 663.77
4. Step 4: Simplify right side
   1,223.30x = 1,120,549.21
5. Step 5: Solve for x
   x = 1,120,549.21/1,223.30
6. Step 6: Final answer
   x = 916.00