Finding the Fourth Proportional to 1,142.09, 1,576.10 and 644.71

Step by Step Solution

1. Step 1: Write the proportion equation
   1,142.09 : 1,576.10 = 644.71 : x
2. Step 2: Convert to fraction form
   1,142.09/1,576.10 = 644.71/x
3. Step 3: Cross multiply
   1,142.09x = 1,576.10 × 644.71
4. Step 4: Simplify right side
   1,142.09x = 1,016,127.43
5. Step 5: Solve for x
   x = 1,016,127.43/1,142.09
6. Step 6: Final answer
   x = 889.71