Finding the Fourth Proportional to 1,142.17, 1,576.21 and 644.82

Step by Step Solution

1. Step 1: Write the proportion equation
   1,142.17 : 1,576.21 = 644.82 : x
2. Step 2: Convert to fraction form
   1,142.17/1,576.21 = 644.82/x
3. Step 3: Cross multiply
   1,142.17x = 1,576.21 × 644.82
4. Step 4: Simplify right side
   1,142.17x = 1,016,371.73
5. Step 5: Solve for x
   x = 1,016,371.73/1,142.17
6. Step 6: Final answer
   x = 889.86