Finding the Fourth Proportional to 1,085.57, 1,498.12 and 665.68

Step by Step Solution

1. Step 1: Write the proportion equation
   1,085.57 : 1,498.12 = 665.68 : x
2. Step 2: Convert to fraction form
   1,085.57/1,498.12 = 665.68/x
3. Step 3: Cross multiply
   1,085.57x = 1,498.12 × 665.68
4. Step 4: Simplify right side
   1,085.57x = 997,271.54
5. Step 5: Solve for x
   x = 997,271.54/1,085.57
6. Step 6: Final answer
   x = 918.66