Finding the Fourth Proportional to 1,081.51, 1,492.39 and 639.42

Step by Step Solution

1. Step 1: Write the proportion equation
   1,081.51 : 1,492.39 = 639.42 : x
2. Step 2: Convert to fraction form
   1,081.51/1,492.39 = 639.42/x
3. Step 3: Cross multiply
   1,081.51x = 1,492.39 × 639.42
4. Step 4: Simplify right side
   1,081.51x = 954,264.01
5. Step 5: Solve for x
   x = 954,264.01/1,081.51
6. Step 6: Final answer
   x = 882.34