Finding the Fourth Proportional to 1,081.46, 1,491.72 and 639.34

Step by Step Solution

1. Step 1: Write the proportion equation
   1,081.46 : 1,491.72 = 639.34 : x
2. Step 2: Convert to fraction form
   1,081.46/1,491.72 = 639.34/x
3. Step 3: Cross multiply
   1,081.46x = 1,491.72 × 639.34
4. Step 4: Simplify right side
   1,081.46x = 953,708.81
5. Step 5: Solve for x
   x = 953,708.81/1,081.46
6. Step 6: Final answer
   x = 881.87