Finding the Fourth Proportional to 1,142.91, 1,577.01 and 638.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,142.91 : 1,577.01 = 638.72 : x
2. Step 2: Convert to fraction form
   1,142.91/1,577.01 = 638.72/x
3. Step 3: Cross multiply
   1,142.91x = 1,577.01 × 638.72
4. Step 4: Simplify right side
   1,142.91x = 1,007,267.83
5. Step 5: Solve for x
   x = 1,007,267.83/1,142.91
6. Step 6: Final answer
   x = 881.32