Finding the Fourth Proportional to 1,142.71, 1,576.90 and 638.59

Step by Step Solution

1. Step 1: Write the proportion equation
   1,142.71 : 1,576.90 = 638.59 : x
2. Step 2: Convert to fraction form
   1,142.71/1,576.90 = 638.59/x
3. Step 3: Cross multiply
   1,142.71x = 1,576.90 × 638.59
4. Step 4: Simplify right side
   1,142.71x = 1,006,998.11
5. Step 5: Solve for x
   x = 1,006,998.11/1,142.71
6. Step 6: Final answer
   x = 881.23