Finding the Fourth Proportional to 1,081.32, 1,491.88 and 639.06

Step by Step Solution

1. Step 1: Write the proportion equation
   1,081.32 : 1,491.88 = 639.06 : x
2. Step 2: Convert to fraction form
   1,081.32/1,491.88 = 639.06/x
3. Step 3: Cross multiply
   1,081.32x = 1,491.88 × 639.06
4. Step 4: Simplify right side
   1,081.32x = 953,400.83
5. Step 5: Solve for x
   x = 953,400.83/1,081.32
6. Step 6: Final answer
   x = 881.70