Finding the Fourth Proportional to 1,288.08, 1,930.72 and 663.42

Step by Step Solution

1. Step 1: Write the proportion equation
   1,288.08 : 1,930.72 = 663.42 : x
2. Step 2: Convert to fraction form
   1,288.08/1,930.72 = 663.42/x
3. Step 3: Cross multiply
   1,288.08x = 1,930.72 × 663.42
4. Step 4: Simplify right side
   1,288.08x = 1,280,874.79
5. Step 5: Solve for x
   x = 1,280,874.79/1,288.08
6. Step 6: Final answer
   x = 994.40