Finding the Fourth Proportional to 1,131.88, 1,561.50 and 665.92

Step by Step Solution

1. Step 1: Write the proportion equation
   1,131.88 : 1,561.50 = 665.92 : x
2. Step 2: Convert to fraction form
   1,131.88/1,561.50 = 665.92/x
3. Step 3: Cross multiply
   1,131.88x = 1,561.50 × 665.92
4. Step 4: Simplify right side
   1,131.88x = 1,039,834.08
5. Step 5: Solve for x
   x = 1,039,834.08/1,131.88
6. Step 6: Final answer
   x = 918.68