Finding the Fourth Proportional to 1,086.72, 1,500.18 and 638.54

Step by Step Solution

1. Step 1: Write the proportion equation
   1,086.72 : 1,500.18 = 638.54 : x
2. Step 2: Convert to fraction form
   1,086.72/1,500.18 = 638.54/x
3. Step 3: Cross multiply
   1,086.72x = 1,500.18 × 638.54
4. Step 4: Simplify right side
   1,086.72x = 957,924.94
5. Step 5: Solve for x
   x = 957,924.94/1,086.72
6. Step 6: Final answer
   x = 881.48