Finding the Fourth Proportional to 1,131.56, 1,561.86 and 665.96

Step by Step Solution

1. Step 1: Write the proportion equation
   1,131.56 : 1,561.86 = 665.96 : x
2. Step 2: Convert to fraction form
   1,131.56/1,561.86 = 665.96/x
3. Step 3: Cross multiply
   1,131.56x = 1,561.86 × 665.96
4. Step 4: Simplify right side
   1,131.56x = 1,040,136.29
5. Step 5: Solve for x
   x = 1,040,136.29/1,131.56
6. Step 6: Final answer
   x = 919.21