Finding the Fourth Proportional to 1,131.50, 1,561.47 and 665.84

Step by Step Solution

1. Step 1: Write the proportion equation
   1,131.50 : 1,561.47 = 665.84 : x
2. Step 2: Convert to fraction form
   1,131.50/1,561.47 = 665.84/x
3. Step 3: Cross multiply
   1,131.50x = 1,561.47 × 665.84
4. Step 4: Simplify right side
   1,131.50x = 1,039,689.18
5. Step 5: Solve for x
   x = 1,039,689.18/1,131.50
6. Step 6: Final answer
   x = 918.86