Finding the Fourth Proportional to 1,142.73, 1,576.98 and 638.58

Step by Step Solution

1. Step 1: Write the proportion equation
   1,142.73 : 1,576.98 = 638.58 : x
2. Step 2: Convert to fraction form
   1,142.73/1,576.98 = 638.58/x
3. Step 3: Cross multiply
   1,142.73x = 1,576.98 × 638.58
4. Step 4: Simplify right side
   1,142.73x = 1,007,027.89
5. Step 5: Solve for x
   x = 1,007,027.89/1,142.73
6. Step 6: Final answer
   x = 881.25