Finding the Fourth Proportional to 1,142.06, 1,576.28 and 644.71

Step by Step Solution

1. Step 1: Write the proportion equation
   1,142.06 : 1,576.28 = 644.71 : x
2. Step 2: Convert to fraction form
   1,142.06/1,576.28 = 644.71/x
3. Step 3: Cross multiply
   1,142.06x = 1,576.28 × 644.71
4. Step 4: Simplify right side
   1,142.06x = 1,016,236.31
5. Step 5: Solve for x
   x = 1,016,236.31/1,142.06
6. Step 6: Final answer
   x = 889.83