Finding the Fourth Proportional to 1,131.22, 1,561.35 and 665.74

Step by Step Solution

1. Step 1: Write the proportion equation
   1,131.22 : 1,561.35 = 665.74 : x
2. Step 2: Convert to fraction form
   1,131.22/1,561.35 = 665.74/x
3. Step 3: Cross multiply
   1,131.22x = 1,561.35 × 665.74
4. Step 4: Simplify right side
   1,131.22x = 1,039,453.15
5. Step 5: Solve for x
   x = 1,039,453.15/1,131.22
6. Step 6: Final answer
   x = 918.88