Finding the Fourth Proportional to 1,191.87, 1,644.81 and 660.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,191.87 : 1,644.81 = 660.72 : x
2. Step 2: Convert to fraction form
   1,191.87/1,644.81 = 660.72/x
3. Step 3: Cross multiply
   1,191.87x = 1,644.81 × 660.72
4. Step 4: Simplify right side
   1,191.87x = 1,086,758.86
5. Step 5: Solve for x
   x = 1,086,758.86/1,191.87
6. Step 6: Final answer
   x = 911.81