Finding the Fourth Proportional to 1,200.57, 1,656.67 and 669.40

Step by Step Solution

1. Step 1: Write the proportion equation
   1,200.57 : 1,656.67 = 669.40 : x
2. Step 2: Convert to fraction form
   1,200.57/1,656.67 = 669.40/x
3. Step 3: Cross multiply
   1,200.57x = 1,656.67 × 669.40
4. Step 4: Simplify right side
   1,200.57x = 1,108,963.27
5. Step 5: Solve for x
   x = 1,108,963.27/1,200.57
6. Step 6: Final answer
   x = 923.70