Finding the Fourth Proportional to 1,081.82, 1,492.90 and 640.09

Step by Step Solution

1. Step 1: Write the proportion equation
   1,081.82 : 1,492.90 = 640.09 : x
2. Step 2: Convert to fraction form
   1,081.82/1,492.90 = 640.09/x
3. Step 3: Cross multiply
   1,081.82x = 1,492.90 × 640.09
4. Step 4: Simplify right side
   1,081.82x = 955,590.36
5. Step 5: Solve for x
   x = 955,590.36/1,081.82
6. Step 6: Final answer
   x = 883.32